Craig Eastmond is a major doubt for Colchester United's trip to play Charlton Athletic in the Capital One Cup on Tuesday night.
The U's midfielder limped out of the U's 2-2 draw with Oldham Athletic on the opening day of the new League One season, after suffering an ankle injury in the first half.
Eastmond was replaced by George Moncur, who went on to score on his Colchester debut and secure the U's a share of the spoils.
The former Arsenal midfielder is now facing a battle to be fit for the U's trip to the Valley for the League Cup first-round tie against the Addicks.
Colchester manager Joe Dunne said: “Unfortunately, Craig has injured his ankle.
“He’ll be struggling a bit but in that area, we still have one or two players who can come in and do a job."
If Eastmond is ruled out, the likes of Moncur, Marcus Bean and Sammie Szmodics will all be vying to start against Charlton.
For five pages of coverage of the U's opening-day game with Oldham, see Monday's Daily Gazette.