When “Showtime” Shawn Porter was 10 years old, he played football against kids who were 12 and 13.

“It doesn’t sound that big,” he said this week, “but back then, when you’re 10 going up against preteens, it’s a big deal.”

Porter has continued to not back away from a challenge, which is why he’s eager to face unbeaten Errol “The Truth” Spence in a Fox pay-per-view welterweight unification bout on Sept. 28 at Staples Center in Los Angeles. Spence (25-0 with 21 KOs) will be defending his IBF 147-pound championship, while Porter (30-2-1, 17 KOs) is putting up his WBC welterweight belt.

“We were never allowed to shy away from any challenge, and that’s the way I’ve lived my life,” Porter said this week. “So when it comes to taking on Errol Spence, to me it’s like taking on any other fighter. It’s not like I’m taking on the boogeyman or the best welterweight in the world. To me, I’m taking on another great, exciting fighter and I’m going to beat that great exciting fighter.”

While Spence is a boxer, Porter is a brawler who likes to wear-down the opposition by applying relentless pressure. He hopes the tactic works against Spence.

“I’m going to go at him like I’ve gone at Keith Thurman, like I’ve gone at Danny Garcia, and the list goes on,” Porter said. “If he can’t handle the roughness, then you will find out real soon. We’ll be rough, we’ll be hard, we’ll be rugged, we’ll keep the pressure on him and we all know pressure bursts pipes.”

Spence can apply his own brand of two-fisted pressure and has said he plans to give Porter his first loss by knockout. Porter hasn’t lost since dropping a unanimous decision to Keith Thurman in 2016. He only other loss was a majority decision to Kell Brook in 2014.

“I think he may be trying to psych himself out into thinking he can do it,” Porter said of Spence’s KO prediction. “I think I have a proven chin. We never want to get hurt, but I’ve taken some pretty good shots from some top guys out there and I’ve managed to handle that and come out on top.”

This is the latest in a series of competitive match-ups in a deep welterweight division. Terence Crawford holds the WBO belt while Manny Pacquiao is the WBA champion. Former champions Thurman, Danny Garcia and Amir Khan are also hoping for another chance at a world title. It would be logical for the winner of Spence-Porter to face one of the other belt-holders in hopes of crowning an undisputed champion someday soon.

“I think myself and Errol Spence are the No. 1 and No. 2 guys,” Porter said. “You can decide who you want to be No. 1 and No. 2, but the best part about it is No. 1 is going to fight No. 2 and one is about to get eliminated. The way I beat Errol Spence, I think that will see me as the No. 1 guy in the division.”

The UFC, meanwhile, kicked off its promotion of UFC 244 at the Garden on Nov. 2 by announcing the bout will be for a newly created “Baddest MotherF—ker In The Game” belt. Nate Diaz and Jorge Masvidal will meet in the main event.

It’s a non-title bout, though the BMFITG belt apparently has just as much significance.

“I’ll physically have that belt when I come back to New York,” UFC president Dana White promised a public audience. “This fight is a big deal for the division and for who is next in the title picture. It’s a huge fan-favorite fight.”