Defender's departure to fierce rivals Manchester United would be another blow for Arsenal after losing Bacary Sagna to Manchester City

Arsenal captain Thomas Vermaelen has agreed a deal in principle to join Manchester United this summer.

United must now agree a fee with Arsenal after the World Cup, but Vermaelen hopes to move to Old Trafford and is preparing to leave the Emirates.

Central defender Vermaelen only has one year remaining on his Arsenal contract and has found himself pushed out of manager Arsene Wengerís first-choice team by Laurent Koscielny and Per Mertesacker.

New United manager Louis van Gaal is desperate to strengthen Unitedís defence and believes Vermaelen can find his best form under him.

The 28-year-old has been at Arsenal for five years after signing from Dutch club Ajax. He got off to a superb start with the Gunners, but injuries curtailed his progress.