Floyd Mayweather has urged Conor McGregor to speak to his UFC bosses and "make a fight happen" between the pair.
Retired five-weight champion Mayweather and MMA star McGregor have spent the past year talking up a cross-codes showdown in a boxing ring.
McGregor has never fought professionally in the ring, leading many to dismiss a possible clash between the pair as a mismatch.
However, Mayweather, who turned 40 on Friday, has defended the Irishman's stand-up skills and says he is a "hell of a fighter."
"I'm here, let's make it happen," Mayweather said to Showtime's Steve Farhood.
"Every time McGregor goes out there and competes and wins, he does it standing up. When Conor McGregor did lose, he lost on the ground. He didn't lose standing up so here a hell of a fighter.
"He's a very, very tough competitor and he has a will to win. Also, the UFC gloves are no different to boxing gloves, they just a little bit smaller. But if a guy got power, he got power and Conor McGregor got power."
Mayweather, who retired after defeating Andre Berto in September 2015 to match Rocky Marciano's perfect 49-0 record, has previously said he would only lace up his gloves again for McGregor and demanded a guaranteed $100m.
"We already know what my number is. My number is there and he has to get his thing in order with his team. Once Conor McGregor speaks to the UFC and his bosses, then we can make it happen because we all know that Floyd Mayweather is his own boss.
"We got Showtime PPV, Mayweather Promotions - which is the past, the present and the future of sports entertainment so let's make the fight happen."
