UFC star Dominick Cruz thinks it's an absolute joke Floyd Mayweather says he can get Octagon ready by the end of 2018 ... saying he'd crush Floyd with 1 ARM if he made the move that quickly.

"He's only got 2 tools -- he doesn't have the other 8," Cruz told the guys on the TMZ Sports TV show (airs tonight on FS1).

FYI, Floyd recently told us he's applying for a pro MMA license -- and set 6 to 8 months as his timetable for getting ready to rumble with a UFC foe (probably Conor McGregor).

Dom says Mayweather would be lucky if he could nail JUST takedown defense in that amount of time ... and that's if he puts in consistent work with UFC welterweight champ Tyron Woodley -- a stud college wrestler. 

Sounds like fightin' words to us -- your move, Floyd.

http://www.tmz.com/2018/03/19/dominick-cruz-floyd-mayweather-one-arm-ufc-mma/