Silvestre's arrival forces Kolo shuffle

The Arsenal boss wants to pair Silvestre, 31, with captain William Gallas at the heart of an all-French back four following his £750,000 switch from Old Trafford.

But that will leave no place for Toure, 27, so Wenger is contemplating shifting him into a central midfield berth, which he has only occasionally filled since moving to north London in 2002.

The Ivory Coast international could have an early taste of his new role in Saturday's trip to Fulham, with Arsenal still desperately short of midfield cover.

Cesc Fabregas is not expected to return to action following a hamstring injury until the second leg of the Champions League qualifying tie with FC Twente next Wednesday, while Alexander Hleb, Gilberto Silva and Mathieu Flamini were all sold during the summer.

Brazilian youngster Denilson was partnered in central midfield by Emmanuel Eboue, a right-back, in last Saturday's win over West Bromwich Albion but Wenger is hopeful Toure can make the position his own - especially as moves for Liverpool star Xabi Alonso and Udinese's Gokhan Inler are foundering.

Silvestre has signed a two-year contract to become the first United player to move to Arsenal since Brian Kidd in 1974.

The France international had been a target for Manchester City, Bordeaux and Paris Saint-Germain but was determined to relocate to Emirates Stadium once he became aware of Wenger's interest.

He said: "I'll remember my time with United fondly but I'm ready for a new challenge.

"Arsenal are known for playing technical and skilful football and they have a young but experienced squad. I'm really excited about this next stage of my career."

Wenger added: " We have a strong squad but a young squad and Mikael's versatility, experience and calibre will provide the extra depth we need to reinforce our challenge for honours this season. His adaptability will serve us well and it's a big plus that he has top-level experience and a great understanding of football in the Premier League."

Ferguson signed Silvestre from Inter Milan in 1999 after he began his career with Rennes, who he left for the San Siro in 1998.

Silvestre enjoyed considerable success at Old Trafford, winning four Premier League titles, the FA Cup and the League Cup in his 361 appearances with the club.

But his final season at United was hampered by a knee injury sustained against Everton in September 2007, which restricted him to six competitive appearances.