Sunderland boss Steve Bruce will monitor the fitness of on-loan defender John Mensah for the rest of the season before deciding whether or not to make a permanent move for him.
The Ghana international has been impressive when he has played for the Black Cats this season after arriving in a loan deal from Lyon in August last year.
However, Mensah has managed only 13 appearances to date because of a back condition which has led to a series of niggling injuries.
Sunderland's medical team have now come up with a fitness programme in order to manage the situation, and the defender has started the last four games despite only training with his team-mates once a week.
While Bruce has been left marvelling at Mensah's ability, he knows the fitness issue is a big factor he must consider when making a decision over a permanent move.
Bruce said: "He has still got three years left at Lyon, so ultimately we will have a conversation when the time is right and we will just see what develops and see what happens from now until the end of the season.
"He is a very, very good player. The problem he has got is the ongoing problem with his injuries.
"But we have now got him into some sort of programme which benefits him. There's no disputing that he does tire badly in games, which is normal because he doesn't train a lot.
"But he can get away with it because of his natural ability. He is a fantastic defender, it is just an absolute crying shame, the ongoing problems he has.
"But as a defender, he is unbelievable, superb, as good as you get."
Midfielder Lee Cattermole is another Sunderland player struggling for fitness as he battles against a hamstring-related condition which has limited him to just seven appearances since December.
He is rated at 50-50 for Saturday's Premier League clash with Birmingham after sitting out the City game, and Bruce admits his problems are an increasing concern.
He said: "Lee came back against Manchester City and played the full game and then the following week, did his hamstring and missed five games.
"It's a horrible, niggling injury which he can't seem to shake off, so you could say it is a concern.
"He has had all sorts of scans and we can't seem to find out what the problem is. It's a strange one, to say the least."