Sussex captain Tom Haines is facing five to six weeks out after suffering a broken hand against Leicestershire.
The 23-year-old batter was hit by a ball from Foxes paceman Chris Wright in the 11th over of their County Championship match on Monday.
The opener retired injured on 24.
Haines has made 604 runs in nine matches in Division Two this season, including a career-best 243 against Derbyshire in April.
