Derby County centre-back Matt Clarke is set to be out of action for three months with a calf injury.
That is according to Rams boss John Eustace who revealed the "massive blow" ahead of the club's first home game of the new Championship season.
Clarke - who started 45 games for Derby last season - missed the club's opener against Charlton Athletic due to a calf issue.
The full extent of the set back was not immediately revealed, though Eustace has since revealed that the former Middlesbrough man will now be out until the festive period.
"I think he'll be out for 12 weeks," Eustace said of Clarke on BBC Sounds.
"That's a huge blow for us of course it is, but it gives somebody else the opportunity to step up and do well."
Clarke is joined on the treatment table by full-back Derry Murkin who joined the club from Utrecht in February.
After a positive start to life in the East Midlands Murkin picked up a hamstring issue before the end of the season, with a return to the pitch still some way off.
Eustace admitted Murkin could also miss much of the early part of the campaign, and asserted the need to keep the 27-year-old around the squad during a difficult time in his career.
He continued: "It's quite a big setback for him, a big setback for us as well.
"The most important thing is his mental health, making sure he's okay. He's come over here from a different country and he's living on his own so it's really important he feels he has the right environment to get back.
"There will be opportunities for him to help the group, not just on-field but off too."
Derby will look to register their first points of the season when they welcome Cardiff to Pride Park on Saturday afternoon.
