England Under-19 batsman Moeen Ali has joined Worcestershire.
Moeen, whose cousin Kabir also plays at New Road, moves from Warwickshire in a three-year deal.
Worcestershire chief executive Mark Newton said: "Moeen is one of the outstanding young players in English cricket at present.
"We believe several counties have shown an interest in him. I am sure he will be challenging for a starting spot from the start of next season."
Warwickshire chief executive Colin Povey said the county was disappointed Ali had turned down a new contract.
"He has come up through our age group and academy structures and looked set for a long career here at Edgbaston," said Povey.
"He is a talented and ambitious cricketer and feels he might develop quicker in a new environment. Time will tell whether he has made the right decision but we wish him well."
Ali captained England Under-19 in their 2006 World Cup campaign.
He was given five starts in the Championship this season, hitting 172 runs at an average of 21.5.