Ronan Fay, 24 and from Co Tyrone, helped secure the 2011 World Pool Championships for Team Ireland after he clinched the deciding frame.
Fay, from Dernmore Close in Coalisland, received an eight month sentence suspended for three years for wounding one of the brothers.
He was one of three men involved in the attack outside a Newry nightclub in the early hours of 24 April, 2011.
Newry Crown Court Judge Brian Sherrard told Fay and the others that the violence and ferocity of the shocking CCTV footage had been hard to watch.
Sitting in Belfast's Laganside courthouse, Judge Sherrard said while Fay had admitted a significantly lesser count, his involvement could not be underestimated, although he acknowledged his remorse was sincere and what he did was entirely out of character.
He added that while Fay had distinguished himself as a talented pool player, he was now said to be suffering from a medical condition.
However, Judge Sherrard said that apparently had not prevented him becoming involved in the terrible and violent assault.
Defence QC Billy McCrory said that initially after an altercation had broken out, Fay had thought he was helping out a friend, but by his plea accepted he had stuck a blow.
Fay, a pool player of international standing, said Mr McCrory, was now very contrite and that the behaviour exhibited on that night was wholly uncharacteristic and for which he was totally ashamed.
Prosecutor Michael Chambers said that Fay and brothers Kevin and Darren Corr, of Pine Grove, Coalisland, attacked the two brothers after they attempted to get on to a hire bus back to Co Tyrone after a night out in the Cornmarket area of Newry.
Defence QC Terence McDonald for 23-year-old Kevin Corr said normally such a person would not be before the courts, and deeply regretted his involvement.
However, he fully accepted that even a person of good character, where drink was involved, can have a dramatic fall from grace.
Defence QC Greg Berry for his 26-year-old brother Darren, said his involvement was half-hearted and had started off after he intervened to help a friend.
Mr Berry said that the blows he inflicted would have caused minimal injury, if any injury at all.
Judge Sheppard, accepted that like Fay, the Corr brothers had acted totally out of character and an aborration, but they had been involved in a vicious attack on defenceless victims.
Kevin Corr was jailed for 20 months to be followed by 28 months on supervised licenced parole, while his brother Darren was freed after he agreed to complete 200 hours community service.