Mickelson's addition means the Sept. 15-18 field could have at least two of the world's top four golfers. Defending champion Vijay Singh is currently No. 2 behind top-ranked Tiger Woods, and Mickelson is No. 4.
Joe Hardy, founder of 84 Lumber, is again expected to make a big push to land Woods, who received a seven-figure appearance fee for a 1997 exhibition at the Nemacolin Woodlands resort where the tournament is staged.
Woods initially committed to play in last year's tournament but changed his mind following the United States' one-sided loss in the Ryder Cup the week before.
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