Liverpool legend Ray Houghton has slammed Swansea City defender Ashley Williams over his clash with Manchester United striker Robin van Persie.

Williams booted the ball into the back of RvP's head late in the second-half of yesterday's 1-1 draw.

"For me, it's unnecessary. Acts like that are cowardly," Houghton told talkSPORT.

"It's a bit like spitting in someone's face. That's not showing strength of character or showing you're a hardman. It's a cowardly act."