Hove: Mushtaq Ahmed will have surgery on Monday to determined the extent of an injury to his right knee, Sussex announced Friday.
Mushtaq has suffered a fresh cartilage tear but has been told he will not know the full extent of the injury until the operation has been carried out.
Former Pakistan leg-spinner Mushtaq underwent keyhole surgery in May.
The worst case scenario is that Mushtaq is out of the season but, if the tear is only a minor one, he could be back in time for the title-holders' County Championship match against Lancashire at Old Trafford on Aug 6.
Mushtaq took 90 first-class wickets for Sussex last season at an average of just over 25 apiece as the south coast club were crowned county champions.
The Pakistani also notched up a century of dismissals when Sussex first won the title five years ago.