Amir Khan Says He'd Kick Manny Pacquiao's Ass

Manny Pacquiao's good friend Amir Khan says there ain't no friends in the ring ... telling TMZ Sports, he wants to fight Manny ... and he'd kick his ass.

We got Khan in L.A. yesterday and asked him about the idea of fighting Manny -- a bout rumored to be on the horizon -- and what it would be like to fight a friend and former training partner.

"I've been around training with him for many years, and sometimes friends have to fight. Sometimes you put your friendship to the side for business."

Khan went on to say that if he does step in the ring with Pacman -- who just knocked out Lucas Matthysse -- he has no doubt he'll get the job done.