Nottinghamshire captain Steven Mullaney is set to undergo knee surgery this week.
The all-rounder has been troubled by the problem for a number of weeks as it prevented him from bowling in the County Championship.
Mullaney will now miss a number of Vitality Blast games, although a timescale on his return has not been set as further assessments are needed once his operation has taken place.
The former Lancashire player is a key member of the Notts squad in all-formats, with head coach Peter Moores dealt a blow heading into Thursday's Blast opening game against defending champions Worcestershire Rapids at Trent Bridge.
Despite being hampered by the injury, Mullaney has been one of Notts' better players in a largely disastrous campaign in Division One of the Championship.
