Floyd Mayweather and Conor McGregor both say a crossover showdown is likely to happen.
Mayweather signed off his professional career with a points win over Andre Berto in September 2015 to take his record to a perfect 49-0.
But the former five-weight world champion, who turns 40 next month, has in recent months been linked with a so-called 'super fight' in a crossover encounter against McGregor.
The Irishman insists his next fight will be in a boxing ring and called out Mayweather, branding him 'scared'.
'I am enjoying the little games we're playing the back and forth. Let's give the fans what they want,' said McGregor.
'I believe this is the first billion fight. I think it will happen at the end of this year or the start of next year.
'I believe the next time I step into a combat arena will be through the ropes with 10oz gloves on.'
Mayweather is keen for the bout to go ahead but has no timescale.
He said on Sky Sports 1: "Most likely the fight between me and Conor McGregor will happen.
"That's the only fight that will get me back in the ring. He's going to do a job on his side and we are going to do a job on my side and hopefully all the fans in the UK come over and support me.
"I don't know (when it will be), I need to communicate with my team, the fight hasn't been made yet, but it is all about entertainment so hopefully we can make it happen."