Duff was subsequently ruled out of the Republic’s crunch World Cup qualifier with Switzerland tomorrow, and returned to London for more treatment and further scans with Chelsea’s own medical team.

Should that diagnosis reveal the need for a minor operation, then the winger is likely to be unavailable until the start of next month, meaning he would miss the Premiership matches against Bolton, Everton and Blackburn as well as the Champions League clash with Real Betis and Carling Cup tie at home to Charlton.

Chelsea are yet to confirm the extent of Duff’s injury, but the player’s agent believes the attacking midfielder will need to go under the knife to correct the problem.

“Damien does need some type of surgery,” his agent Pat Devlin claimed.

Devlin added in the London Evening Standard: “I don’t think it will be anything too major, but as far as I’m aware, he will be out for two to three weeks.”

With virtually all of his first-team regulars away on international duty, the Chelsea manager will be hoping for a clean bill of health when his squad returns on Thursday morning, for what will be a busy few days with next week also seeing the resumption of their European campaign.

Full-back Wayne Bridge, meanwhile, continued his recovery from a broken ankle to build up his match fitness with another run-out for the reserves against Watford on Monday night, playing 65 minutes of the 1-1 draw with West Ham at Aldershot.