Casey is taking the cautious approach in his comeback
Paul Casey's chances of overhauling Martin Kaymer as the season's top money winner on the European tour have taken a blow because of his rib injury.
The world number four has now been ruled out of next week's Alfred Dunhill Links Championship in Scotland.
The injury has kept Casey out since the first week of August.
"I am disappointed as it is a fantastic event, but I know that coming back too soon could undo all the rehabilitation work I've done," he said.
"It has been a very frustrating time, but I feel my patience is being rewarded having now completed several light practice sessions with no ill effects.
"I am looking forward to building on this over the next few weeks to get my game in shape for my return.
"My first event back will now be the Volvo World Match Play Championship where I hope I can get my Race to Dubai campaign back on track."
Kaymer is also currently out of action having undergone surgery after breaking toes in a go-karting accident a month ago.
The lay-offs of Casey and Kaymer have opened the door to Rory McIlroy, Lee Westwood and Ross Fisher to take over at the top of the standings next week.
Kaymer tops the standings with 1.98m euros, 17,000 ahead of Casey and more than 150,000 ahead of McIlroy in third.