Derbyshire's Shiv Thakor will miss the rest of the season after suffering a stress fracture of his back.
A scan has confirmed the extent of the problem, ruling him out of the final three games of the campaign.
"It's really disappointing for Shiv. He's been brilliant. He's really come of age," said head coach John Sadler.
Thakor has enjoyed a fine season, scoring 606 first-class runs at an average of 67 and claiming 22 wickets, including career-best figures of 5-36.
"He worked very hard in the winter on all aspects of his game and he's reaped the rewards," Sadler added.
"He's a vital part of our side, so to not have him available now is really unfortunate.
"He'll have a bit of time away now, but I'm sure when he's able to he'll start working hard and get himself going again ready for next season.
"It will now give someone else the opportunity to play and learn in the final few games."