Manchester United manager Sir Alex Ferguson believes signing Robin Van Persie from Arsenal has been his biggest transfer of this summer and can make a difference to bring back the title from City rivals Manchester City.

United boss signed Van Persie for £24 m from League rivals Arsenal. The Dutch International was also been targeted by Roberto Mancini but Ferguson was successful in signing the former Arsenal skipper.

Ferguson said Van Persie is getting better and better and has already made an immediate impact being the top scorer for the club this season scoring eight goals.  The Dutch International along with Wayne Rooney has found a great deal of partnership which could create trouble to any defense in the world.

“Robin’s performances are getting better all the time now. He’s got there with his fitness, which is fine now. Last week against Stoke and on Tuesday against Braga, his movement was fantastic. I really was impressed with that” Ferguson said while speaking to The Mirror.

"Robin’s cross last week [against Stoke] for Wayne’s goal was the kind of cross a defender hates - it was whipped in, between the last defender and the goalkeeper. It was brilliant. I thought it was really top, top stuff. Hopefully it does make a difference. We bought him for that reason - to make a difference”

“When we realized Robin wasn’t going to sign for Arsenal, we did our very very best to get him at our club and we succeeded. We’re delighted with that and the signs have been terrific. Robin is a great professional. He trains very well and he has made an impact immediately" Ferguson went on to add.

Van Persie’s arrival at the club has impacted Javier Hernandez first-team chances. However Ferguson has a different opinion saying it has created a healthy competition among Van Persie, Rooney, Hernandez and Danny Welbeck.

“We bought him in to give us maturity up front, and also the flexibility of different types of players," Sir Alex explained. With Danny Welbeck, Chicharito, Van Persie and Wayne Rooney we have fantastic alternatives. The four of them could make the difference"