Former five division world champion Floyd Mayweather Jr. (49-0, 26 KOs) is back in the gym and back to sparring.

Mayweather sparred six rounds with undefeated prospect Devin Haney (15-0, 10 KOs), who is preparing for his own ring return on June 24th.

For his part, McGregor is also hard at work in the gym. The MMA star has released numerous training videos over the past few weeks - and in all of those videos McGregor is training as a boxer. His camp is reportedly contacting boxers to work as sparring partners if the Mayweather deal comes together.

Mayweather, 40-years-old, retired from boxing in September 2015 after dominating Andre Berto over twelve rounds. He announced in April that he was coming back to the ring - but only for a fight with McGregor.

McGregor has been out of the cage since November, when he became the UFC’s first simultaneous two-division champion when he stopped Eddie Alvarez at Madison Square Garden to win the lightweight (155-pound) belt.

As far as McGregor's portion of the deal, the fighter and the UFC were able to iron out the financial terms last month - which was a big piece of the puzzle as the UFC have McGregor under an exclusive contract and the fighter was risking the possibility of a legal battle by going around them to make the deal.

Last month, Showtime Sport head Stephen Espinoza advised BoxingScene.com that his network will be involved in the pay-per-view and the promotion of that event. Mayweather held an exclusive six fight contract with Showtime, which finished out when he beat Berto - but the boxer has a very close relationship with the network and his fighters are showcased on their airwaves on a regular basis.