Chris Coleman admits he doesn't yet know when Lamine Kone will return for Sunderland after he suffered a groin injury.
Kone missed the 3-1 defeat to Sheffield Wednesday after picking up the injury in the second half of the Good Friday win at Derby County.
Kone and John O'Shea were superb against the Rams but Coleman was unable to call upon the same centre-back pairing for the visit of the Owls, with Marc Wilson recalled.
Coleman is now sweating on the severity of Kone's groin injury ahead of Saturday's trip to Elland Road to face Leeds United.
When asked if Kone would be back for the weekend, Coleman added: "I've no idea. It's a groin problem he picked up on Friday night midway through the second half.
"He had a light session on Sunday, wasn't comfortable, and was even worse on Monday morning. We don't know yet."
Kone's enforced absence was the only change for the Wednesday defeat. One of the standout performers was Lynden Gooch, who again caught the eye.
Coleman added: "I had a chat with him about a month ago because I thought there were certain things he needed to work on and he's gone away and worked on them, fair play to him.
"He's played very well in the U23s and he's got his chance. Friday night he did well and on Monday he ran himself into the ground.
"All our players have had chances but it's consistency we've struggled with. He's not losing as much possession, he's getting us up the pitch. He did very well."