Manny Pacquiao to undergo surgery on 'significant tear' in his rotator cuff and could be out of the ring for up to a year

Pacquiao re-injured his shoulder in the fourth round during his loss to Floyd Mayweather and could face disciplinary action for not revealing it pre-fight

Mayweather won by unanimous decision as Pacquiao struggled throughout (Getty Images)

Manny Pacquiao will undergo surgery later this week on the "significant tear" that he suffered during his comprehensive defeat to Floyd Mayweather last weekend, but could face disciplinary action for failing to inform officials about the should injury that he suffered three weeks before the $320m mega-fight.

Pacquiao revealed after his defeat that he was unable to throw punches with his right hand due to a torn rotator cuff. Having suffered an original injury less than a month before the richest boxing match in history, Pacquiao chose to keep the injury quiet, only for it to worsen in the fourth round of the fight when he rocked Mayweather for the one and only time over the 12 rounds.

Orthopaedic surgeon Dr Neal ElAttrache confirmed that the Filipino great will undergo surgery at some point this week, and will be out of action for between four to six months.

But there are fears that he could be missing from the ring for up to a year, with ESPN.com’s Dan Rafael claiming a rotator cuff injury of this kind usually results in a lengthy lay-off that would also call in to question whether ‘Pacman’ would ever fight again.

ElAttrache examined Pacquiao on Monday at his Kerlan Jobe Orthopedics office in Los Angeles, with the eight-weight world champion leaving Las Vegas with his right arm in a sling.

However, the 36-year-old could also be fined and suspended for failing to disclose his shoulder injury in the build-up to the match. The Nevada Athletic Commission’s chairman Francisco Aguilar confirmed on Monday that Pacquiao will be investigated by the state attorney general’s office, having ticked the box that said “no” on the eve of the Vegas showdown which asked if he was carrying an injury.

Aguilar said: "We will gather all the facts and follow the circumstances. At some point we will have some discussion. As a licensee of the commission you want to make sure fighters are giving you up-to-date information."

Bob Arum, Pacquiao’s promoter, issued a statement to say that the injury was disclosed to the US Anti-Doping Agency, although their remains confusion over whether the used of an anti-inflammatory injection was given the green light or not.

"As Manny has said multiple times, he makes no excuses," the statement read. "Manny gave it his best."

Pacquiao struggled after re-injuring his shoulder in the fourth round (Getty Images)

After the fight, Pacquiao’s trainer Freddie Roach said that a request for a pain-killing injection had been rejected.

Roach added: "We thought at one time we'd postpone the fight, but as the weeks went on it was getting better and I was happy with his performance. I thought the progress was good enough."

Roach talks to Pacquiao during his defeat to Mayweather (Getty Images)

Mayweather threw and landed more clean punches than Pacquiao (Getty Images)

USADA were only a third-party and were responsible for testing both fighters for banned substances in the months leading up to the bout as well as afterwards, and the head of USADA Travis Tygart confirmed that they had no information regarding the details of an injury to Pacquiao.

"We had no medical information, no MRIs, no documents," said Tygart.

"It was not an anti-doping issue. The real question is why his camp checked 'no' on the disclosure. Either they made a terrible mistake to not follow the rules or they were trying not to give information to the other side. I'm not sure there's a middle ground."

Pacquiao did not have much success against Mayweather (Getty Images)

Pacquiao’s camp requested the painkilling injection just two hours before the fight, but had the request denied as his injury could not be proven.

"It's not just the fact he didn't fill out the question completely, it was that he wasn't honest and they didn't tell us a month ago when he had the shoulder injury," Nevada Athletic Commission executive director Bob Bennett said. "They're not obligated to, but two hours before the fight they wanted a shot that's a pain killer in essence. That put us in a very precarious position."