Boxing is the most punishing of contact sports, so it takes a special athlete to have both the drive and physical capability to return to the ring after initially hanging up their gloves.
Some return for the money, others for a shot at redemption, while old scores to settle can be reason enough for ex-pros to step onto the canvas once more. The latter was the case in Grudge Match, as Robert De Niro and Sylvester Stallone got together for one final dust up.
But what about some notable others who have pursued a second career in the fight game? GiveMeSport looks at four of them...
The 'Hitman' was one of Britain's favourite boxers, attracting huge support wherever he went. His first defeat came against Floyd Mayweather after previously going 43 bouts without a blemish on his record. Hatton announced his retirement in 2009, two years after his second round knockout against Manny Pacquiao. He said: "Boxing started off as a habit and it ended up giving me some money and making me a little bit of a better person. But I don't think I will have a fight again."
However over three years after his last fight, Hatton made his comeback. In a sold out Manchester Arena he was knocked out by Yacheslav Senchenko in the ninth round and officially announced his retirement.
After the fight he said: "I am just gutted. I am not a failure. That is not how my career should end but I have to have a good think about it now."
Another British boxer, but not quite as well loved as Hatton, David Haye had many big fights in his career, losing a unification bout to Wladimir Klitchklo having got the better of 7 ft 1 in Nikolai Valuev. It was an amazing feat considering Haye weighed seven stone less than his Russian counterpart.
In 2011 Haye did not renew his boxing contract, meaning that he would retire aged 30. He said "That'll be 20 years of getting punched in the face, which is a long enough time. I set my goals and achieved them so unifying the titles is the cherry on the cake but if it doesn't happen it wasn't meant to be and I've just got to get on with my life".
However, Haye got into a disagreement with Derek Chisora after the latter's fight with Vitali Klitschko resulting in a post fight brawl between the two Brits. They set up a fight (that had to be licensed by the Luxembourg boxing association), as they were both under investigation by the British association, and Haye won by K.O in the fifth round.
He then was meant to fight Tyson Fury but this was postponed and then cancelled after Haye sustained a cut eye then a shoulder injury, drawing criticism from many boxing fans.
Recognised by many as thee greatest fighter of all time, he was stripped of his boxing license between 1967-1971 after refusing to be in the U.S Army.
Ali retired in 1979 after being comfortably beaten by Leon Spinks. However he returned to boxing due to his need for money despite him being way past his best. His opponent Larry Holmes didn't really want to fight him as he knew it would be a walkover, and so it proved as Holmes K.O'd him in the 11th round. Ali fought once more against Trevor Berbick but was no where near his best, losing in 10 rounds. This was his final fight.
Arguably the most famous comeback in boxing history, Muhammad Ali was the only boxer to stop George Foreman within the scheduled distance. In 1977 after losing a bout with Jimmy Young, Foreman claimed he had a near death experience after falling ill with heatstroke in the dressing room. He pleaded with god to help him and became a born again Christian and minister of a church.
10 years later, aged 38, he shocked the world by announcing his return to boxing. By the time 1991 came around he was given a shot at the World Heavyweight title. He lost to Evander Holyfield but was praised for his performance. However, in 1994 he capped a remarkable comeback by knocking out overwhelming favourite, Michael Moorer, in the 10th round.
Foreman eventually announced his finally retirement three years later after a loss to Shannon Briggs, aged 48.