Floyd Mayweather Jr. has lapped up being in the spotlight over the years so he was never going to shy away from celebrating his 40th birthday.

The man widely regarded as the pound-for-pound king of boxing leaves the 30s behind on Friday amid ongoing rumblings over a potential fight with big-talking UFC star Conor McGregor.

Mayweather will reportedly be ringside on his big day to watch young fighters in an event at Pechanga Resort & Casino in Temecula, which has been arranged by his promotional company.

The legendary fighter, who retired with an unbeaten record after 49 professional bouts, and his 'Money Team' are then said to be heading for a glitzy party with the great and good of Hollywood.

As a birthday gift to Mayweather fans, here we reflect on five of the American showman's best fights.

Mayweather v Genaro Hernandez - October 3, 1998

The experienced Hernandez had only lost once in 40 fights before putting his WBC super featherweight title on the line against a 21-year-old Mayweather.

But a one-sided bout at the Las Vegas Hilton proved to be his last, as Mayweather won a first world title when Hernandez's brother and trainer, Rudy, conceded the fight after eight rounds.

The nimble Mayweather picked the man nicknamed 'Chicanito' off with a brilliant technical display of boxing, landing 221 punches and sinking to his knees in tears after he was awarded the fight to be crowned world champion for the first time in his 18th professional fight.

Mayweather v Diego Corrales - January 20, 2001

After months of trash talk, Mayweather let actions speak louder than words by outclassing Diego Corrales in an MGM Grand masterclass to retain his super featherweight title.

Corrales was floored five times by 'Pretty Boy', who was simply too quick for his powerful opponent and never looked troubled.

Mayweather unleashed a relentless barrage on the previously unbeaten Corrales, who went down three times in the seventh and twice in the 10th as he hung in there but never stood a chance with the champion at his brutal best.

Mayweather v Oscar De La Hoya - May 5 2007

A record-breaking purse was agreed for a blockbuster bout back at the MGM Grand, where Mayweather stepped up from welterweight to face Oscar De La Hoya.

Huge hype was stirred by the feuding fighters in the build-up to the 154-pound WBC showdown and they did not disappoint when the talk stopped in the Nevada desert.

De La Hoya dished out brutal shots to the body and head, but Mayweather got his tactics spot on as he refused to get into an all-out brawl, defending brilliantly and putting together effective combinations.

Mayweather was awarded a split decision to claim the super welterweight strap, much to the fury of a crowd that was mainly backing De La Hoya.

Mayweather v Ricky Hatton - December 8 2007

The all-conquering Mayweather retained his WBC world welterweight title by dominating Hatton to inflict a first professional defeat on the Englishman in his 44th fight.

An imperious Mayweather was just too savvy for Hatton, who took it to the favourite in the early rounds but failed to do any damage.

Hatton ran out of steam and Mayweather had plenty in the tank, landing vicious right hands and putting the Mancunian on the canvas twice in the 10th round to bring an end to the fight.

Mayweather v Saul 'Canelo' Alvarez - September 14, 2013

Alvarez was also unbeaten before pitting his wits against Mayweather at MGM Grand, but his perfect record was emphatically ended.

The flame-haired Mexican was given a lesson by a man 13 years his senior, with a 36-year-old Mayweather given a majority decision to secure the WBC and WBA light-middleweight titles.

There was talk of Mayweather being given one of his biggest tests for many years, but he improved his record to 45-0 with apparent ease after peppering Alvarez - who candidly stated after the fight that he had no answer to one of the boxing greats.