Worcestershire captain Joe Leach will miss the rest of the season with a stress fracture of his back.
Leach was only able to bowl four overs in the Pears’ one-wicket One-Day Cup victory over Warwickshire on 7 June.
The 27-year-old all-rounder is Worcestershire’s leading wicket-taker in first-class cricket this season, with 23 dismissals at 22.08.
Head coach Kevin Sharp is yet to decide who will lead the team in their One-Day Cup semi-final on Sunday.
Worcestershire will face either Nottinghamshire or Kent in the last four and will discover their semi-final opponents on Thursday.
“It is a big blow and Joe is gutted and quite upset at the minute,” said Sharp. “He has played such a major part for the club over the last few years.
“It is life. Bowling is a very physical job. Joe has had very few injuries but very rarely do bowlers go through their career without some sort of injury.
“It means there will be an opening for others that might not have had an opportunity. We want the lads to stand up and be counted – and I’m sure they will.”
Leach’s loss will hit bottom club Worcestershire particularly in the County Championship, with the former Shropshire all-rounder having been their leading wicket-taker in four-day cricket for the past three seasons.
They have the option of recalling veteran Australian seamer Steve Magoffin, who returned to the county during the winter essentially for red-ball duties, but has so far played in just two Championship matches.