Conor McGregor is working hard in the gym -- €” and to make us all believe he really might fight Floyd Mayweather Jr.

Both fighters have been feeding the rumor, despite UFC boss Dana White insisting the fight never will happen. And McGregor has been training with former IBF and IBO champion boxer Chris van Heerden, who's apparently a big fan of McGregor's boxing.

A message to South Africa from @TheNotoriousMMA after great sparring pic.twitter.com/xVn8L26UIn

— Chris van Heerden (@TheHeat001) May 17, 2016

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"There is no easy road to any place worth going l" @thenotoriousmma on form today slick & Quick @boxnburnbrentwood pic.twitter.com/HtR6omfDzo

— Chris van Heerden (@TheHeat001) May 17, 2016

"People miss the opportunity of success because they are afraid of taking risks" #Respect @TheNotoriousMMA Thank you pic.twitter.com/5B1jzQD61l

— Chris van Heerden (@TheHeat001) May 16, 2016

All thats been asking!I've sparred with TOP fighters & @TheNotoriousMMA Boxing game is Right-Up there 👊🏻💯 @BoxNBurn pic.twitter.com/gLcNygYq39

— Chris van Heerden (@TheHeat001) May 15, 2016

What a Humble life Experience having the pleasure going Toe 2 Toe with The Biggest name in UFC @thenotoriousmma pic.twitter.com/d1FjNMyEUZ

— Chris van Heerden (@TheHeat001) May 14, 2016

He's not the only one. Tony Jeffries, a former Olympic medalist and the co-owner of the LA gym where McGregor is sparring, appears to be impressed as well.