Among the many subplots entering Saturday's welterweight title unification bout in Los Angeles between Errol Spence Jr. and Shawn Porter is just how much history the two share leading up to this pay-per-view bout. Not only did Porter's father, Kenny, serve as an amateur coach for Spence, Porter himself was somewhat of a mentor or "big brother" to Spence after he turned pro. The two fighters also have experience sparring one another in training.

Nearly a decade later, it's apparent that Spence and Porter have put their friendship aside for the sake of business and opportunity. What that has created is more than a few tense moments during the buildup to this weekend's must-see fight at the Staples Center. 

Both fighters recently sat down with CBS Sports for an extended conversation that can be heard in its entirety on this week's "State of Combat with Brian Campbell" podcast (listen to the interviews in the embed below). The pair of welterweight champions recalled the early days of how they first met, why the goodwill between them has unraveled in recent months, and what effect their relationship will have on Saturday night's fight.

The beginning

Porter: "My dad comes home one day telling me about this young kid he caught wind of that he saw in the tournament. The kid was really good and from Dallas, Texas. [I'm thinking,] 'Cool.'"

Spence: "Shawn Porter's dad took me to a lot of international tournaments as an amateur. We were overseas a lot, and he would lead the amateur camps that happened at Colorado Springs at the Olympic Training Center. Shawn actually helped me get ready for the Olympics along with other pros like 'Kid Chocolate' [Peter Quillin] and Adrien Broner. Shawn's dad Kenny was the coach, so we created a friendship."

Porter: "Next thing I know, this kid is making the Olympic team, and it's 2011, and I had been a pro for a few years, and they wanted some professional fighters to come out and train with the Olympic team. They chose myself because my dad was part of the Olympic program. We trained a whole week."

Spence: "Me and Kenny have always been cool. We always talked and things like that. Shawn has always been a cool guy. Every time we see each other, we talk it up, mutual respect and things like that. It has always been cool with us."

Porter: "Errol Spence and myself, we did about four rounds of sparring back then, and outside of that, it was always the norm. The boxing community is small, and you always see these guys around."

Spence: "[Sparring with Porter] is not an advantage at all. That was a long time ago. He was a professional and I was an amateur, so my mentality changed a lot. I don't think they remember the sparring, but if they do, they can't go off of that."

Porter: "My dad feels that he knows how Errol Spence thinks and how Errol Spence reacts. He thinks he has really good insight on Errol Spence's mental game, and I think that's going to play a big role in this fight."

Kenny Porter told CBS Sports in August that he has experienced being in the unbeaten Spence's corner during multiple amateur losses and that it's an advantage. Asked whether that might play a role, Spence was much more dismissive.

Spence: "If he said that, then he's not as good of a coach as he thinks he is. I haven't lost since the quarterfinals of the Olympics [in 2012] to a Russian fighter [Andrey Zamkovoy] and [Kenny Porter] wasn't in my corner. Usually I win, so if he has been in my corner when I lost, he's not as good as he thinks he is. With Barry Hunter and a lot of other coaches, I have a winning record with them, so I guess he doesn't mesh out as good as he thinks he did."

Porter: "For a while, [Spence] was talked about. I don't even know his record when people really started talking about him and saying he was dangerous to the division."

Spence, who made his pro debut in November 2012, began to create chatter months earlier following a competitive -- and reportedly heated -- sparring session against Floyd Mayweather who was trying to get back in fighting shape after a brief stint in jail. Although Kenny Porter witnessed the sparring session in Las Vegas, Spence said he never considered turning pro with Porter as his trainer and went as far as laughing at the suggestion.

Spence: "No, not at all. It's just never something that was put in my head. I think I have one of the best coaches [Derrick James] in boxing. We mesh perfectly, and with Kenny and the style he has with Shawn Porter, it's not a style that I'm wishing to have or even mimic. Whatever they do, it works for them and it's something that works for them only."

Porter: "[Spence] and I have always been cordial, but I think the friendship that has been portrayed by the media isn't exactly the friendship that we have even though we have always been polite and cordial with one another. I remember the first time I said I'm going to have to fight this guy is when I recognized that he had been put in line for the IBF title."

Spence: "It has always been like that. Since I turned pro, he has been fighting at 147, and I knew I would be fighting Shawn Porter. It had been planted in my head even though I have always been friendly and cordial to him."

The idea for the fight finally became real just seconds after Porter's decision win over Danny Garcia in October 2018 to capture the vacant WBC title. Spence entered the ring inside Barclays Center and commandeered the microphone to say, "We good friends, I love your daddy, but let's get it on." Porter smiled confidently and replied, "Do I look scared?"

errol-spence-2012-olympics-getty.jpg
Errol Spence (red) fighting Andrey Zamkovoy at the 2012 London Olympics. Getty Images

Friendly fire

The kickoff press conference to announce the bout took place in late July during Manny Pacquiao-Keith Thurman fight week in Las Vegas. Although it began cordially with Spence and Porter speaking with reverence toward each other, somewhere along the way things changed dramatically.

Porter: "[The whole friendship thing] went out the window, didn't it?"

Spence: "That's just the competitive spirit of myself and him. It's something where we might be friends and I might be cool with his dad, but at the end of the day, I don't want to lose."

Porter: "I think we both understand where we are at right now. This guy is trying to take food off of my plate. We are both in a position right now where we understand that we have to win this fight. You see us in the ring after our fight, 'I love you, I love your dad, but I want to fight you.' The next thing you know, there's no friendly chatter at all and it's all about the business. I wouldn't have it any other way."

Spence: "My dream is to become unified champion and the undisputed champion of the world. I have to get through him, and I believe I have to go after my dream and something I've been working hard for above our friendship, and I'm going to have to put our friendship to the side."

Porter: "Errol Spence is very competitive. He loves what he does and loves hurting people, which I appreciate because that's going to make for excitement, a great fight and will make this the fight of the year."

Spence: "We will pick [our friendship] back up after the fight, and it's guaranteed we will have more respect for each other after."

The tenor of the press conference seemed to change for good, however, when Spence chose to stop respecting what Porter brings to the table. During a particularly colorful exchange in which the normally mild-mannered Spence began to use profanity and argue about what the fight will look like, he stared Porter in the eye and defiantly declared, "If you try to box me, I'm going to knock your ass out."

Porter: "I didn't know you heard what he said. When I heard him say that, I think he's trying to intimidate me and maybe even believes that me boxing from the outside and not being aggressive may be the best chance he has to win the fight."

Spence: "It's basically what I meant. I'm a guy of few words, and when I do say something, I mean it and I stand on that. I don't take nothing back."

Porter: "At the end of the day, the jaw-jacking and talking is a bit of a psychological game that makes a guy question himself and rethink his game plan and that's not happening on this side of the ring."

Spence: "So if he tries to box me, I'm going to punish him. Even if he moves forward, it's going to be the same outcome anyway. So it's kind of a double-edged sword for him if he boxes or tries to bang and fight."

Porter: "Right now, it's hard to say who Errol Spence is right now. He has multiple videos [on social media] kind of trying to slander me for the sake of words or down talk me. Then we pop out in Dallas -- and no one knows this -- but we run into him at the restaurant and we are buddy-buddy again. No cameras around or no media around, and in a lot of ways he was that same amateur kid that my dad had gone on some trips with and coached in the corner with. He was that same kid that I had known for a long time, but it changes once the camera comes."

Spence: "If he thinks that way, he will be in for a rude awakening."

Porter: "Shawn Porter, he never changes. You never have to guess or wonder which Shawn Porter you are talking to. But right now, I think Errol Spence has a lot of questions that he is trying to figure out for himself."

Spence: "I'm a guy who is very mentally tough. I showed that in the Kell Brook fight, in front of that many fans and on that type of stage. That shows my mental capabilities." 

Porter: "Any fighter can be broken, it all depends on what you are doing to break that fighter. Sometimes staying away from a fighter can break a fighter. That guy can't touch you like he's used to doing. I'm going to break Errol Spence in quite a few different ways, and this fight is going to be a wake up call for him."

Spence: "I'm not worried if he thinks that will happen. Ironically, I think I can break him down mentally and physically and get the stoppage. It's always a mental war when you get into a fight, especially a fight of this magnitude."

Porter: "When we get in the ring, I'm counting on his immaturity and inexperience in the ring. I've had a lot of experiences abroad as an international and amateur competitor. I do expect his immaturity to kick in when things aren't going his way. When the little brother can't get to the big brother, he gets really ruffled up and uneasy and starts to get wild and crazy and I'm expecting to get that this fight."

Spence: "Will Shawn pay a price [for the mind games he's playing]? No, because there will be a price to pay anyway. No matter what he does, I'll be ready. I already have it in my head that I want to punish Shawn and get an impressive knockout. Nothing that he can say can stop me from what I'm thinking. He can only talk more trash and get me to train harder and be more focused."

Porter: "I'm not counting on the public to overrate Errol Spence. I'm counting on Errol Spence to overrate Errol Spence, and that will be clear to him when we get in the ring and he doesn't handle me the way he has handled the other 25 opponents he has had."

Flame lit

Spence has surprised many by how direct and dismissive he has been of Porter's abilities ahead of this fight. Not only has Spence predicted a knockout at every turn, he has characterized Porter as nothing more than an aggressive mauler.

Spence: "I think he's a fighter that is just rough and rugged. He's a guy who is going to come and give his all and try and make it an ugly and rough fight. 

Porter: "Any legendary fighter you have ever seen or anyone who is talked about for a long, long time who has shown their heart in the ring and won over crowds and really destroyed their opponents in the ring, that's who I am."

Spence: "Is Shawn dirty? Definitely. Much to the gentleman that he pretends to be outside the ring, inside he is dirty and rough. He's guy who will use head butts and elbows and basically use anything to pull out the victory. It has worked for him, and he's a champion for a reason, but he showed it in the Andre Berto and Devon Alexander fight -- cutting them with elbows and head butts. He's a guy who can be dirty if you let him."

Porter: "Right now as a fighter, I'm prepared to do whatever it takes to leave such a grand mark in my era, and I will not be denied. That's what makes me so great as a fighter."

 Porter has slightly evolved from the all-or-nothing rugged style that defined his initial run as a welterweight titleholder. In recent wins over Danny Garcia and Yordenis Ugas, he earned close decisions by mixing in boxing from distance and relying on his footwork.

Spence: "I expect the rough Shawn Porter. You can say he evolved but was it for the good or for the worse?"

Porter: "The short answer is I plan to be it all. The short answer is it takes me being everything that I have ever been to beat Errol Spence. It takes me being aggressive and not stopping. But it also will take me using my feet, hand speed, ring intelligence and my reflexes. Knowing when to push forward and when to be a counter puncher."

Spence: "Even the Danny Garcia fight, he barely won that fight. The Ugas fight, he barely won that fight trying to box. I think he's going to come forward and try to make it rough and throw a lot of punches and be in the best shape possible."

Porter: "I have to disagree with [needing to risk it all to win]. As long as I go in with the right game plan and remain smart and on my toes, I don't think it's going to take me risking getting knocked out to win the fight. I think it's going to take me doing the right things. I have every component that it takes. I expect to be so fast, so quick and so sharp that at some point I just leave him behind and just reign as a supreme competitor in this fight. I don't think it takes me leaving my chin out there and swinging non-stop to beat Errol Spence, I just think it takes being the best I can be and I've been very close quite a few times. I'm preparing to have an easy night."

Spence: "If Shawn said he thinks it's going to be an easy night, he's lying. Shawn has never been in an easy fight, it's not his style. Even if it could be an easy fight, he will make it a rough and rugged fight and make it a dog fight. You know he's not telling the truth if he thinks it's going to be an easy night."

Porter: "What gives me the confidence to [beat the boogeyman] is me. I think I know what I can do. I think that it's a blessing that no one has ever seen all of Shawn Porter in one fight. That makes it tough for anyone to prepare for. I think it was tough for Yordenis. It's really tough for guys to get prepared for me, so I think that myself alone, understanding my capabilities and what I can do when I'm focused and ready for the world, I think that's why I am so confident at even taking on a guy who is considered the boogeyman in my division.

"I think, when you take down that big lion, that changes a lot. That changes history. It changes the landscape of the division and where everyone expects things to go right now. I know I'm considered to be the underdog in this fight and not considered to win this fight, but I'm always down for a surprise."