Manny Pacquiao lost the biggest fight of his career on Saturday, and some believe the mega-bout against Floyd Mayweather could end up being his last. Pacquiao will undergo surgery to repair a significant tear in his shoulder, leaving his future in boxing up in the air.

If the procedure goes as planned, Pacquiao still won’t be able to fight for between nine months and a year. Considering his age and future plans, retirement could be a real possibility for the 36-year-old.

"Once you know he has a tear that's not going to heal on its own, then the decision for an active person is you want to try to fix this before it gets bigger," orthopedic surgeon Dr. Neal ElAttrache told "If all goes as expected with the surgery and the rehab is successful, Manny could be back training in about six months. At that point, he will be regaining strength and endurance, and competition is reasonable within nine months to a year. But this is a severe enough tear that it won't heal without being repaired."

Last summer, Pacquiao indicated that he would retire from boxing in 2016. Already a Congressman in the Philippines, Pacquiao told DZMM that there is a good chance he’d run for a seat in the Senate when his career is over. The surgery will keep Pacquiao out of the ring for all of 2015, and possibly most of 2016.

"There’s a big possibility that I will run for Senator," Pacquiao said. "UNA (United Nationalist Alliance party) asked me to join its slate and I am grateful they picked me."

Of course, the injury could push back Pacquiao’s political aspirations. But Pacquiao doesn’t have anything left to prove as a boxer. He’s finally faced Mayweather and taken on the top boxers of his era. There’s no opponent that the boxing world is clamoring to see Pacquiao face.

Pacquiao has recently come back to fight after taking a year off, facing Brandon Rios in November 2013 50 weeks after he was knocked out by Juan Manuel Marquez. But Pacquiao isn’t accustomed to such long layoffs, having never fought less than twice in a year before 2013.

The money could certainly keep Pacquiao in boxing for a few more years. With Mayweather likely gone in 2016, Pacquiao would be the sport’s biggest pay-per-view draw. Pacquiao won’t make the estimated nine figures he earned on Saturday, but he still managed to make over $20 million in November when he fought the relatively unknown Chris Algieri. While Pacquiao’s career earnings approach $450 million, his reported tax issues could have him seeking another big payday.

A year ago, Pacquiao signed a two-year extension with Top Rank. The contract runs through 2016, and promoter Bob Arum said Pacquiao would fight five times before the contract ended. Because of the injury, that will no longer be the case.

Even if Pacquiao does fight again, the injury all but closes the door on a possible rematch between the top two boxers of their generation. Mayweather is scheduled to fight in September, which he claims will be the last fight of his career.

“My love and my passion for boxing is not the same, like it once was,” Mayweather said at Saturday’s post-fight press conference. “But this is my job. I have to go out there and be at my best doing my job.”

Hours before Saturday’s fight, the Nevada State Athletic Commission didn’t allow Pacquiao’s shoulder to be treated with drugs because his advisors didn’t disclose his injury on the pre-fight questionnaire. According to Arum, the injury flared up in the third round.