Ashton Kutcher's first move after wrapping "Two and a Half Men" could be becoming a world champion in Brazilian Jiu-Jitsu, if he wants it -- no joke -- according to his famous trainer.
Rigan Machado tells TMZ Sports he heard all the haters after Ashton earned his purple belt earlier this year. Detractors thought it was just a case of Hollywood favoritism, but Machado says Kutcher is a serious terror on the mats.
Rigan says Kutcher is the best celeb he's ever trained -- which doesn't seem like a high bar -- but he adds ... Ashton could beat some pros ... "because his background is in [high school] wrestling he learns so fast."
Machado has a big Jiu-Jitsu event scheduled for January ... and says he's invited Kutcher "to come and compete if he wants to, if he decides to compete he will do will good."
We just got an idea for the 'Men' finale ... if Charlie Sheen returns as rumored.