Surrey have lost Conor McKerr for the rest of the season after the young fast bowler was told that he must have a cartilage operation.
McKerr, 22, who has torn the cartilage in his right knee, will now have surgery on Thursday.
Surrey have been hit by international calls and injuries and are currently without 14 players.
It forced them to bring in two loan signings for this week's Bob Willis Trophy game with Essex.
Surrey old boy Laurie Evans has returned on loan from Sussex, while Worcestershire loaned them fast bowler Adam Finch for the week.