United initially suggested he could miss five weeks, with Ferguson saying the injury could be partly down to anxiety over his return as well as a lack of match practice.
The Canadian-born midfielder, who has made only 39 appearances since joining the Red Devils from Bayern Munich in 2007, had played 45 minutes with the reserves and less than 60 seconds of first-team football prior to the game against Wolves.
His previous game of any significance was at Chelsea in September two years ago.
England's best player at the 2006 World Cup finals in Germany has been plagued by knee injuries for two years, undergoing surgery - performed by famed surgeon Dr Richard Steadman - and seeing numerous attempts at a return hampered by pain and tendonitis.
Hargreaves is in the final year of his contract at Old Trafford.
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