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.

Mayweather's adviser, Al Haymon, is involved in serious negotiations to finalize a cross-sports boxing match with UFC superstar Conor McGregor. Both sides are targeting a date in early fall.

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.