SUNDERLAND are conducting further tests on Sebastian Coates this week, with the on-loan Liverpool defender suffering from a troublesome thigh problem.
Summer signing Coates lasted just 45 minutes of his Sunderland debut in last week’s Capital One Cup defeat to Stoke City before he was replaced at the interval as a precaution.
The Uruguayan’s injury is not a serious one and he is still able to participate in the majority of training sessions.
But certain movements are causing him pain and that has prompted Sunderland’s medical department to delve deeper into the source of Coates’ problem.
Sunderland boss Gus Poyet told the Echo: “It’s not serious.
“It was a precaution to take him off against Stoke, but we need to check a few more things.
“It’s a strange one. He can do 90 per cent of whatever action you ask him to do.
“But it’s one particular action when it causes him to feel something in there.
“We want to see if we can do more tests and make sure that it’s right. It would be a shame if he can’t play.”
Coates suffered cruciate knee ligament damage at Liverpool in the summer of 2013, before spending the second half of last season on loan at Uruguayan outfit Nacional to work his way back to fitness.
However, Poyet insists the 23-year-old’s current injury is not related.
It is a problem underneath Coates’ quad muscle which is causing him the pain and it only flares up when he is involved in more demanding movements.
Poyet added: “The problem is very, very deep under the quad.
“He can run up and down, and do sprinting.
“But when he’s in a position where he’s really fighting with a striker and over-stretches himself, or hits a long ball, that’s what causes the problem.
“He can train practically every day.
“I asked him one day to train and only pass it with his left foot. I asked him if he felt it and he said ‘no’.
“Then in the Stoke game, he had a few fights with the striker and he didn’t get injured or pull up. But it was there, so you feel it.”
With Coates’ fellow centre-half Wes Brown also missing last weekend’s stalemate against Swansea through a calf injury, Sunderland had just four defenders available.
Santiago Vergini lined up alongside John O’Shea in the heart of the Sunderland defence and unless Brown returns to fitness, that back line will remain intact against Stoke City this weekend.