MK Dons are set to be without Sean O'Hanlon until the New Year as the defender has undergone knee surgery.
The 26-year-old first sustained the problem during the Dons' League One defeat to Walsall in April.
Since then the injury has been deemed severe enough to require an operation, with a summer date set for the centre-half to go under the knife.
That medical procedure has now taken place, but O'Hanlon is facing a long road to recovery.
"Sean has had an operation and we're not looking to have him back until after Christmas," the Dons' assistant manager Karl Robinson told the club's official website.
"He's a great lad and we wish he was fit, but sometimes you've got to play the hand you've been dealt.
"We now need to get a player in who can perform to the same level that Sean has for the last three years."
O'Hanlon joined MK Dons from Swindon in 2006 and has gone on to make over 130 appearances for the club.
He was voted the club's Supporters' Association Player of the Year for the 2008/09 campaign, while he was also included in the 2008/09 PFA League One Team of the Year.