Chelsea fear that first-choice goalkeeper Petr Cech could miss the start of the season after the Czech Republic international sustained a calf problem during training.
The 28-year-old has had to have a scan on the problem that he suffered while training at Cobham on Tuesday and the club is currently awaiting the results.
The Blues fear that it is a recurrence of the muscle tear that ruled Cech out of action for four weeks in the second half of the 2009-10 season.
He tore the muscle in his calf during the Champions League last-16 first-leg clash against Internazionale in February and was forced to miss his club's next five matches, including the return game against the Serie A outfit.
In better news for the Blues, Yury Zhirkov was able to take part in training for the first time as he battles back from a knee injury.