England seamer Graham Onions could miss the rest of Durham's campaign with an abdominal muscle tear picked up against Nottinghamshire in the One-Day Cup.
The 31-year-old has injured the internal oblique muscle on his left side and is expected to be out for around six weeks.
Durham's season ends after the final Championship match against Warwickshire on Tuesday, 23 September.
"I was obviously devastated when I received the results," Onions said.
"The next six weeks of the season are hugely important and although I don't think I can play for the rest of the season, I'll be doing everything I can to try to get fit and help the lads out during those final few games."
Onions, who has 27 wickets for Durham in all formats so far in the 2014 campaign, has also struggled with a back injury this season.
Meanwhile, veteran spinner Gareth Breese is to end an 11-year spell at Durham when he leaves the club at the end of the summer.
The former West Indies player was part of the 2007 Friends Provident Trophy winning squad and has a total of 150 wickets in List A cricket.
"I'd like to thank Durham for all the opportunities they've given me over the years and really thank the players, both past and present, for all their wonderful support," he said.
"For the immediate future, I'm going to do all I can to try and get us as far as we can in the Royal London One-Day Cup tournament and hopefully I've got a few more performances in me to try and take us all the way."