Michael Owen has not played at Manchester United because Wayne Rooney's so good - Sir Alex Ferguson

Manchester United manager Sir Alex Ferguson has recognised the influence that crocked striker Michael Owen has had on the club's season.

"Michael has been such an important player for us and I know I have not used him as much as I should have," Ferguson explained at his Friday press conference.

The Scot indicated that the sole reason the player has not featured as much as he should is due to the exemplary form shown by Wayne Rooney.

"That is a lot to do with Rooney's form and our choice of playing one striker. He has been a little bit unfortunate with that but we recognise he has made a great contribution.

Since United's free acquisition of Owen last season, following the expiration of the Englishman's contract at  Newcastle United, the forward has made 31 appearances - 11 starts and 20 as substitute - and has scored nine goals.

Owen was withdrawn from the field during the club's recent League Cup final triumph over Aston Villa after his first half strike cancelled out James Milners' opener from the penalty spot.

United boss Sir Alex Ferguson earlier confirmed that Owen would require surgery on his hamstring injury that would keep him out for the rest of the season and rule out any involvement in the World Cup.

"He is a good professional who has been terrific in the dressing room. It is the first time he has had a hamstring injury in four years as well, so it is a disappointment for the lad and a bad blow for us."

The hamstring complaint is the latest injury in a long line of problems that have dogged Owen's career. While with Liverpool in 1999 he incurred a complex hamstring problem, and then suffered a repeat problem in 2001. Four years later he broke his foot, before injuring his cruciate knee ligament in 2006.

He has also suffered a groin injury and an ankle problem in the past couple of years.