Jonny Bairstow will miss Yorkshire's Champions League campaign while he seeks specialist advice on torn cartilage in his right wrist.
It is hoped the England international will be able to avoid surgery and the injury will not interfere with his winter touring plans.
Yorkshire will also be without Bairstow's England team-mate Tim Bresnan, who has been prescribed a rest period before the four-Test tour to India, which starts at the end of October.
The Tykes qualified for the October 9-28 Twenty20 event in South Africa thanks to their runners up finish in last season's Friends Life t20.
Hampshire, the FL t20 champions, are England's other representative in the 14-team tournament.