Aston Villa boss Alex McLeish admits Richard Dunne's injury strikes a huge blow to the club after the defender fractured his collarbone.
Villa will be without the centre-back for eight weeks after he suffered the injury landing awkwardly on his shoulder during Sunday's 1-0 defeat to Manchester City.
Utility player Ciaran Clark will also be sidelined for a month after suffering a medial ligament strain to his left knee during training at the weekend.
Dunne underwent surgery in Birmingham on Monday and manager McLeish knows his absence will be felt by the club.
He said: "We're gutted to be losing the big man (Dunne). He was trying to get us back in the game when he made a tremendous leap but, unfortunately, he landed badly on his shoulder and fractured the collarbone.
"He is a stalwart defender and has been that for the past dozen years or so in the Barclays Premier League.
"It's not good for us to be without such a top player and a defender of his massive experience.
"We wish Richard a speedy recovery and Ciaran, too, from his knee injury. We will look now for someone else to step up to the mark."
The plus point for Villa was the return to full training of midfielder Chris Herd.
He has recovered from an ankle ligament injury which has left him sidelined since December.
Villa hope Herd will be available for the game against Wigan on February 25th.
Herd said: "I'm relieved to be back fit and training with the team.
"I'll be training as hard as I can over the next few weeks to try and work my back into the side.
"It's been really frustrating but I'm glad to be back and I still plenty more games to look forward to this season."
McLeish said: "Chris did his usual in training today in that he gave 100% in the session and worked like a demon. We're really pleased to have him back."