Martin O'Neill is sweating over the fitness of Stephane Sessegnon after his creative midfielder injured his ankle in training.
The 28-year-old will be assessed by Sunderland's medical staff who are not sure of the extent of the injury and have booked him in for a scan on Tuesday afternoon.
The Benin international only returned to training last week after being given an extended summer break following his country's World Cup qualifiers towards the end of last season.
And while O'Neill is expecting him to be fit for the trip to Arsenal for the start of the season he is not going to risk his £6m man in Wednesday's friendly game at Derby.
"Sessegnon hurt his ankle in training yesterday and I don't know whether he will make Wednesday night's game," he told the club's official website.
"Hopefully he will be okay for Saturday's match. He's actually going for a scan this afternoon."