Urijah Faber: Conor McGregor's Tough ... But Nate's Gonna Beat That Ass Again!

Conor McGregor's on the fast track to ANOTHER ass whoopin' ... so says Urijah Faber who tells TMZ Sports the Irish superstar just doesn't have what it takes to beat Nate Diaz.

Faber tried to help Conor prepare for his last fight against Diaz, but his advice fell upon deaf ears.

Now, Urijah says ... despite all of the positive things Conor has going for him -- like toughness and skill -- a victory in the rematch is simply out of the question.

By the way, we also asked 37-year-old Urijah if he was planning on retiring any time soon ... check out what he says.