Manny Pacquiao may not have been 100% in the ring tonight, as a report at Yahoo! Sports says that Pacquiao (57-6-2, 38 KO) fought with an injured right shoulder, and was denied a USADA-approved anti-inflammatory injection by the Nevada State Athletic Commission, as Pacquiao had checked that he had no injuries prior to the bout.

The injury reportedly occurred about three to four weeks ago in training camp, and may require surgery that could sideline the Filipino superstar for the rest of the year. Pacquiao lost a unanimous decision to Floyd Mayweather (48-0, 26 KO) on scores of 116-112, 116-112, and 118-110.

Before you start claiming that it's just an excuse for a losing performance, understand that fighters do get hurt all the time, and that at 36, something like this wouldn't be a major surprise. It sounds like Pacquiao tried to deal with the injury as best he could during the lead-up to the fight, and it just didn't heal in time, and he went ahead with the fight that everyone wanted to see anyway, rather than trying to postpone a fight that might not have gotten a make-up date. Let's hope he doesn't need surgery.