Lewis Grabban could miss Sunderland’s upcoming games against Nottingham Forest and Barnsley.
The on-loan AFC Bournemouth striker was unavailable at Bramall Lane on Boxing Day, and the Black Cats struggled to provide an attacking threat in his absence as Sheffield United cruised to victory.
Speaking after the game, Chris Coleman revealed the club’s top scorer picked up the injury against Birmingham City, but he played on and scored as the ten-man Blues clung on for a point.
And the Welshman is yet to discover whether he will be fit for Saturday’s game against Forest.
“Lewis picked a calf injury up in the last game against Birmingham in the first half,” said Coleman.
“He lasted quite well but it hasn’t settled down and he was just not fit unfortunately.”
He continued: "I don’t know if Lewis will be back for the weekend.
“He played an hour with it Saturday because he had it first half, so it depends whether it settles down between now and then.
“I’m not putting that performance on us missing one player – we are missing eight players, but it has nothing to do with missing eight players – it is to do with us and those that were here.
"All of us here came up short.”
Didier Ndong also missed the trip to Bramall Lane due to an injury picked up against the Blues.
"Didier had an ankle injury Saturday.
“He had a kick so he was not here."
