Errol Spence Jr. delivers a straight right to Lamont Peterson during their IBF welterweight title fight at New York’s Barclays Center on Saturday night. (Al Bello/Getty Images)

Lamont Peterson bristled last week when asked what his approach would be as an overwhelming underdog heading into his next fight. The District boxer didn’t consider himself as such, he said defiantly, despite oddsmakers heavily favoring youthful champion Errol Spence Jr. in their welterweight title bout Saturday night at Barclays Center.

But reality and age caught up with Peterson as Spence administered a thorough beating through seven rounds. By the start of Round 8, Barry Hunter, Peterson’s trainer, had seen enough, stopping the fight with Peterson’s right eye barely open and his face showing the damage resulting from ferocious blows from the International Boxing Federation titleholder.

Peterson (35-4-1, 17 knockouts) lost for second time in his past four fights, leaving his future in doubt ahead of his 34th birthday later this month. Spence, 28, continued his rapid ascent in the sport’s most competitive weight class and remained undefeated at 23-0 with 20 KOs.

“He was getting his shots off,” Peterson said during an in-ring interview. “He was a better man tonight.”

The proceedings tilted significantly toward Spence in the fifth round, when a left hook caught Peterson flush, bringing the crowd of 12,107 to its feel. Peterson stumbled, then tumbled to the canvas while trying to brace his fall with both gloves. Peterson was examined after the round and permitted to answer the bell for Round 6.

But the punishment continued for two more rounds and, after consulting with Peterson’s corner and the attending doctor, referee Harvey Dock signaled for the stoppage.

“I know Lamont. He’s a tough fighter,” Spence said. “A lot of guys would have stayed down [after the knockdown], but he wanted to keep going. That’s the kind of fighter Lamont is.”

The early rounds also favored Spence, a left-hander who commanded the center of the ring while moving Peterson around with jabs. A right hand caught Peterson squarely in Round 2, sending him shuffling backward before he regained his balance and was able to counter.

Spence began to ramp up his attack in the third round, getting through Peterson’s attentive defensive posture to land hits to the body and several times to the head, leaving his face a reddish hue.

Asked in the ring after the bout whether he would consider retirement, Peterson, the former IBF and World Boxing Association champion at 140 pounds, said, “It’s not a decision I have to make right now, but it’s something I will think about the next few weeks.”

Peterson fought for the first time since Feb. 18, 2017, when in his 147-pound debut he beat Russia’s David Avanesyan in Cincinnati to claim a secondary WBA welterweight title. Keith Thurman owns the primary WBA super world welterweight championship.

In early October, Peterson voluntarily relinquished the WBA belt, clearing the way for the showdown with Spence, who won the IBF title last year by traveling to Sheffield, England, the home town of then-champion Kell Brook, and collecting a knockout in the 11th round.

Peterson’s previous three losses came against Timothy Bradley Jr., Lucas Matthysse and Danny Garcia. He also had a draw against Victor Ortiz.

“It was hard,” Hunter said of electing to stop the fight. “If you know Lamont, you know his courage. At the end of the day, this is my son. I don’t care more about boxing than I care about him.”

Peterson’s younger brother Anthony fought on the undercard as a super lightweight, dispatching Luis Eduardo Florez in nondescript fashion via 10-round unanimous decision. Two judges scored the bout 110-89, and a third had it 100-90 in Anthony Peterson’s first fight in nearly two years. He last fought April 1, 2016, defeating Samuel Kotey Neequaye, also in a 10-round unanimous decision, at the D.C. Armory.

Anthony Peterson (38-1, 24 KOs) suffered his lone loss against Brandon Rios, a high-quality opponent, in 2010 via disqualification. He has yet to secure a major title fight.