Manchester United manager Alex Ferguson hopes to have his skipper Roy Keane back in action within six weeks.

The Republic of Ireland international underwent a hip operation on Tuesday that had been expected to sideline him for three months.

But Ferguson now expects his influential midfielder to be fit to play again in October.

"He has had the operation," Ferguson confirmed after United's 1-0 Premiership win over Middlesbrough.

"We expect him to be out in about six weeks. We thought it was maybe a three-month job, but hopefully it is going to be six weeks,"

Keane is already facing a three-match ban after being sent off for elbowing Jason McAteer in Saturday's 1-1 draw at Sunderland.

And he could be handed an additional Football Association suspension for comments made in his autobiography about a horror tackle on Alf-Inge Haaland in April 2001.

United boss Sir Alex Ferguson revealed on Monday that he thought the time was right for his inspirational skipper to sit out.

Keane will miss several Premiership games, but he should be back in time to face title rivals Liverpool and Arsenal in December.

Meanwhile, Keane's book-signing appearances in Ireland will be rescheduled.

The former Republic skipper was to have been in his home city of Cork on Thursday 5 September, in Dublin the following day and Belfast on Monday 9 September.