Manny Pacquiao Freddie Roach
Trainer Freddie Roach adjust Manny Pacquiao's mouth guard during the welterweight unification championship bout on May 2, 2015 at MGM Grand Garden Arena in Las Vegas, Nevada. Getty

Floyd Mayweather has been insistent that he’ll retire after his Sept.12 fight with Andre Berto, which would make a potential rematch with Manny Pacquiao an impossibility. But not everyone is convinced that the sport’s top boxer will call it quits this year, and Pacquiao trainer Freddie Roach wants to see the best fighters of their generation go at it one more time.

“I don’t know where Mayweather’s going right now. I don’t think he’ll stop at 49 fights, I think he’ll fight to 50. I’m hoping that he promotes himself, maybe if he does he can make more money,” Roach told George Gigney of Boxing News.

“Manny would do much better in a rematch, if the shoulder gets better. We were doing well until the shoulder went in the fourth round and we had a tough time after that. I do think we can beat Mayweather 100 percent.”

Pacquiao injured his shoulder while training for his May 2 mega-fight with Mayweather, and he won’t fight again until 2016 because of surgery that he underwent to repair a torn rotator cuff. Since losing a unanimous decision to Mayweather, Pacquiao has said that the injury affected him during the bout.

If Mayweather decides to fight again in 2016, Pacquiao would make sense as a potential opponent. Many casual boxing fans were disappointed in the fight, and a rematch would likely make significantly less. But a rematch would be in both fighters' best financial interests. Their fight set multiple records, making Mayweather at least $220 million for one night’s work, and no other welterweight generates as much attention as Mayweather and Pacquiao.

Amir Khan might be the top option for Pacquiao if he’s unable to secure a second fight with Mayweather. Top Rank CEO Bob Arum has discussed making the bout happen, and Khan has been looking to secure a fight with either Mayweather or Pacquiao for some time. While Roach would be interested in Pacquiao vs. Khan, he has another idea regarding whom the Filipino boxer should take on in his return match.

“I want Danny Garcia, that’s my choice. That’s the easiest fight in the (expletive) world, you can tell his dad [Angel Garcia] that as well,” he said.

“His dad psyched Amir Khan out but he won’t psych Pacquiao out I promise. Pacquiao will knock Garcia out. I like the dad but he talks too much (expletive).”

Garcia recently made the move up to welterweight, defeating Paulie Malignaggi with a ninth-round TKO on Aug. 1 in his first fight at the 147-pound weight limit. Garcia is one of the sports best young fighters, going 31-0 with a win over Khan three years ago. Roach, however, is confident that Pacquiao would win and improve his career record to 58-6-2.

Pacquiao could wait close to a year until he has his next fight. His last such break came when he defeated Brandon Rios in Nov. 2013, winning the bout 11 months after he was knocked out by Juan Manuel Marquez.