Leeds United midfielder David Norris faces up to a month on the sidelines through injury.
The summer signing from Portsmouth limped through to the final whistle of the 3-3 draw with Blackburn last weekend.
Scans have now confirmed that the 31-year-old has torn a thigh muscle and could be sidelined for up to four weeks.
United have already lost fellow midfielder Paul Green to a knee problem which is likely to keep him out until October, while Michael Brown continues to struggle with a persistent hamstring injury.
Whites boss Neil Warnock admitted it was a setback to lose Norris to add to his midfield problems.
"It's another blow and I'm really disappointed for him. He's had a great start to the season," Warnock told the Yorkshire Evening Post.
"He'll be looking at three to four weeks so it's not long-term but we've already lost Paul Green and we've got Michael Brown struggling with a hamstring strain. We're looking thin in that area now."