Leonard won the 1996 Buick Open; Azinger ranks 37th on the PGA Tour's career earnings list; and Clarke has played for Europe in five Ryder Cups.
The Buick Open will be earlier this year, ending July 1 instead of in early August, and the schedule change might mean Woods won't make his sixth straight appearance and ninth of his career.
Woods said May 21 that he intends to play, but he and his wife are expecting their first child in July. Woods has said he won't miss the birth, even if it means skipping a major.
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