Cowboy Cerrone -- I'LL FIGHT CONOR MCGREGOR

With Rafael dos Anjos pulling out of his big fight with Conor McGregor at UFC 196 -- Donald "Cowboy" Cerrone is throwing his Stetson in the ring to take Raf's place.

RDA suffered a broken foot during a training session -- leaving the UFC scrambling to find a suitable replacement for Conor for the March 5th fight ... one of the biggest UFC events of the year.

Now, Cerrone says he's game ... with Cowboy's manager Josh Jones telling FOX Sports they've already reached out to the UFC saying he's down to fight.

So far, no official decision has been made -- but it's gotta happen fast ... so stay tuned.