It was the biggest fight of his life, one that would make a shot at the heavyweight championship a realistic possibililty, and Mike Perez turned in a star-making performance.
It's hard, though, for Perez to celebrate his most significant win. He's filled with nothing but sadness when he recalls the events of Nov. 2, 2013, in the Theater at Madison Square Garden in New York.
His biggest night will always be remembered tragically.
Magomed Abdusalamov, Perez's opponent that night, showed amazing courage and toughness. He fought hard, with grit and determination, and through plenty of pain.
But Perez was better, and went on to claim a hard-fought and impressive 10-round victory in his HBO debut.
Abdusalamov left the ring under his own power and went to a local hospital to have a hand checked. But it turned out that he had swelling on his brain and underwent emergency surgery.
For weeks, Abdusalamov teetered on the brink of life and death. He's since been moved to a rehabilitation facility and is expected to survive, but he'll never be the same. Not only will he never fight again, but life as he knew it is gone. He's forever changed, and his family must deal with a mountain of medical bills.
Perez (20-0, 12 KOs) will return to the ring Saturday at the Bell Centre in Montreal to face Carlos Takam (29-1, 23 KOs) in a 10-rounder on HBO that should advance him another step along the way toward a title bout.
But Perez, a Cuban who defected to Ireland, has to deal with the aftermath of the Abdusalamov tragedy. Everyone who steps into the ring understands that immense danger lurks around the corner, but prays they never have to confront it.
Perez said he was deeply saddened by the injuries Abdusalamov suffered, but insists he hasn't let it affect his performance.
"The first couple of days back in Big Bear [Calif.] were a little tough, but my coach [Abel Sanchez] was very helpful and I felt much better, like I was supposed to be back in the gym doing my job," Perez said. "It felt good to be back after a couple days and getting ready for another fight so soon."
Sanchez isn't so sure he believes Perez. For weeks after the fight, fans of Abdusalamov abused Perez, posting photos and making incendiary comments on his Facebook page.
Perez began to feel that he'd done something wrong and was deeply troubled by Abdusalamov's plight. He poured his heart out to his girlfriend, Sanchez, promoter Tom Loeffler and manager Patrick Thomas.
It was a hard time in his young life and something one is never prepared for, no matter how experienced he may be.
"It was extremely difficult for him," Sanchez said. "We had to convince him that it wasn't his fault. He wasn't intentionally trying to hurt Mago. He was just doing his job. We had to convince him that it could have been him, and not Mago, in that situation. It was a brutal fight and both guys gave and took a lot of punishment."
Sanchez said Perez didn't seem to have problems in sparring, but the real test will come during a fight.
The gym is a safe zone, where boxers feel comfortable. Though many fighter injuries come in the gym, fighters often don't recognize that because they're better protected in sparring and feel more in control than they do when they're under the bright lights in a real fight.
If Perez has Takam hurt, his natural instinct would be to jump on him and put him away. One of Perez's flaws, Sanchez said, is that even though he has good boxing skills, he's so aggressive going for the finish that he often leaves himself open to counters.
Sanchez, though, isn't 100 percent convinced that Perez will be able to pull the trigger if he has a chance to put Takam away. He worries that he may be haunted by the memories of the Abdusalamov fight and might be unable to finish Takam.
"I'd be foolish to say I didn't have that concern," Sanchez said. "All of us as a team have that concern. We won't know for sure until he gets into that position. The mind is a difficult thing to understand."
But Perez said, "I'm ready to fight," and he's hopeful that an impressive victory will get him a bout against a highly rated opponent.
Sanchez said that touted heavyweight Bryant Jennings, who fights on Jan. 25 on HBO, already turned down a bout against Perez.
Perez, though, first must deal with the demons that come with seriously injuring an opponent.
It's easy to talk about it, but the only proof will be in the ring.
Sanchez has great belief in Perez's talent and thinks he can become one of the world's finest and most popular heavyweights.
Perez is a teammate of middleweight champion Gennady Golovkin and has benefited from watching the way Golovkin goes about his work, Sanchez said.
Perez will have to deal with the Abdusalamov situation on his own, though.
Whether he can overcome it remains to be seen. If he can, boxing may finally have a promising heavyweight prospect to get excited about.
If he can't, and no one would be critical of him if he couldn't, he'll be the latest in a long line of contenders who couldn't quite reach their ultimate goal.