Chelsea winger Damien Duff says there is an 80 percent chance he could suffer a recurrence of the dislocated shoulder he sustained when he fell awkwardly against Fulham in December.

"I am hoping the shoulder will heal itself with a lot of rehabilitation but the doctors say there is an 80 percent chance the injury I had before Christmas will come back," the Ireland international told the Daily Express newspaper on Tuesday.

If Duff dislocates his shoulder again it could become a regular occurrence, as it did for former England captain Bryan Robson.

"Players often use shoulders when they fall, particularly someone in his (Duff's) position who go past people with speed," said Chelsea's club doctor Neil Frazer. "They need to be able to land and, if he dislocates it again, he's very liable to recurrent dislocation.

"A percentage of sportsmen who have such a fall suffer recurrent dislocations. The last big name you may remember was Bryan Robson."

Duff, who has also been struggling with an Achilles injury, is hoping to return for Chelsea on Wednesday.

"I expect to be back to face Portsmouth (in the premier league) on Wednesday," said Duff. "I had better be because there are some big ones after that and I don't want to miss any of them."

Chelsea meet title rivals Arsenal in both the league and FA Cup in the next couple of weeks and travel to Stuttgart for a Champions League tie later this month.