LAS VEGAS – Manny Pacquiao threw fewer punches than Floyd Mayweather, 435-429, which few observers could have predicted.

But Pacquiao's camp is claiming he had a right shoulder injury that he suffered three to four weeks before the fight. He had taken anti-inflammatory shots that were approved by the United States Anti-Doping Agency during camp. He requested to take a shot after arriving in his locker room shortly after 6 p.m. PT, but was denied by the Nevada Athletic Commission.

Trainer Freddie Roach said the injury occurred when Pacquiao threw a right hand during camp approximately a month ago. There was no doctor available to explain the injury, but Pacquiao promoter Bob Arum said it was the same injury that Lakers star Kobe Bryant suffered that ended his 2014-2015 season.

Manny Pacquiao (R) throws a right against Floyd Mayweather Jr. on May 2. (AP) More

Bryant had surgery to repair a torn rotator cuff.

One source said he might need surgery that could keep him out for up to nine months, but that was not confirmed at the news conference.

"We felt the [rehabilitative] work that was done on the shoulder duing training would give him the opportunity to use the right hand," promoter Bob Arum said. "We were disappointed when in the third round the injury kicked up again, but this is always the case in sport. ... He heals the injury, thinks he’s conquered it and it flares up again."

The drugs he wanted to take were not performance-enhancing, but because he checked on a medical form that he had no injuries, the commission denied him the shot. The drugs were Bupivacaine, Celestone and Lidocaine.

Chairman Francisco Aguilar said he would not comment until after the news conference when Pacquiao had addressed it.

"The first I heard of this was at 6:08 [p.m. PT] when he arrived in the locker room," he said.

He said one of the issues was proof of the injury.

"I have no proof of the injury," Aguilar said. "If he told us on Friday, we would have gotten the MRIs and there are a lot of things we could have done."