Sunderland v Villa: Clark in line for return but Herd doubtful
Clark sat out the matches against Fulham, Norwich City and Swindon Town with a knee complaint but has recovered in time for today's trip to the Stadium of Light.
But manager Paul Lambert revealed Herd is struggling after being forced off during the Capital One Cup victory at Swindon on Tuesday night.
"To be fair Chris Herd's injury is not as bad as we thought," said Lambert.
"He's still a doubt but it's not too bad. The scans have come back okay.
"But Ciaran is back in the squad. I will decide later on what team we go with."
Charles N'Zogbia is expected to be out for several weeks with a knee injury.
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