Manny Pacquiao’s next fight will be No.63 since he became a professional boxer. At 35 years old, it’s one of the most important bouts of his career.

Pacquiao will face Timothy Bradley in a rematch of their 2012 welterweight title match. Though it was a controversial decision, Bradley walked away with a split decision and the victory. In his second try, Pacquiao has a lot on the line.

Even though Pac-Man is coming off a win, his upcoming fight will determine a lot, in regards to his career. Pacquiao defeated Brandon Rios in November by unanimous decision. In his first fight after two straight losses, Pacquiao took on an opponent that had little chance of beating him. If he wants to prove that he’s still one of the best boxers around, Pacquiao will have to get the job done against Bradley.

“Manny knows this is do or die for him,” Bradley told ESPN. “If Manny doesn’t win this fight then his career will be over. So this is a must-win situation for Manny Pacquiao. I already beat him once. This fight is for redemption to get credit I didn’t get in the first fight because people felt I didn’t win. That’s what it’s about for me. For him, he has to come to prove that he can earn that title. He’s got to come earn it back, and it’s the end of the road if he doesn’t.”

Following his loss to Bradley in 2012, Pac-Man was knocked out by Juan Manuel Marquez and lost without controversy. His defeat of Rios helped him get a win under his belt, but a victory against Bradley could be critical for Pacquiao. After such a lengthy career, there are questions surrounding how much Pacquiao has left.

Before facing Rios, trainer Freddie Roach said he’d advise Pacquiao to retire if he didn’t win the fight. While Roach hasn’t said the same thing regarding Pacquiao vs. Bradley II, a bad loss could mean that retirement isn’t far away.

A potential mega-fight between Pacquiao and Floyd Mayweather is highly unlikely to happen in 2014, but the odds might become near impossible if Pacquiao can’t win his next bought. The demand to see the best boxers of their generation face off lost a lot of steam when Pacquiao suffered his losing streak. Another defeat would give Mayweather even less reason to agree to the fight.

Pacquiao has been in the professional ranks for two decades. Three losses in four tries could be a sign that it’s time to move on.