Chris Smalling has hailed the impact that Robin van Persie has made on Manchester United since his summer arrival from Premier League rivals Arsenal.

The Dutch international has scored 15 goals in all competitions for the Red Devils from just 21 outings.

It is that statistic that has resulted in Smalling heaping praise on his teammate.

"Obviously he only came in the summer and didn't have much of a pre-season," said Smalling. "But he came straight into the matches and has been such a threat.

"He is putting teams on the back foot and making our job easier at the back."

Van Persie found the net as United defeated Sunderland 3-1 yesterday afternoon.