Phil Mickelson

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Phil Mickelson celebrates after winning the Masters golf tournament at the Augusta National Golf Club in Augusta, Ga., in this April 11, 2004 file photo. (AP Photo/Dave Martin)

Phil Mickelson hugs last year's Masters winner Canada's Mike Weir after being presented his green jacket after winning the Masters championship with a nine-under-par at the Augusta National Golf Club in Augusta, Ga., Sunday, April 11, 2004. (AP Photo/Dave Martin)

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Phil Mickelson gives a thumbs-up to fans as he walks to the ninth hole during the second round of the Houston Open golf tournament, on Friday, April 4, 2014, in Humble, Texas. (AP Photo/Patric Schneider)

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Phil Mickelson tees off on the 12th hole during the second round of the Houston Open golf tournament on Friday, April 4, 2014, in Humble, Texas. (AP Photo/Patric Schneider)

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Phil Mickelson watches his drive on the fifth hole during the first round of the Shell Houston Open, Thursday, April 3, 2014, in Humble Texas. (AP Photo/Patric Schneider)

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Phil Mickelson, right, smiles at his caddie Jim Mackay as he birdies on the fourth hole during the first round of the Houston Open golf tournament on Thursday, April 3, 2014, in Humble Texas. (AP Photo/Patric Schneider)

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Phil Mickelson tees off on the fifth hole during the first round of the Shell Houston Open golf tournament, Thursday, April 3, 2014, in Humble Texas. (AP Photo/Patric Schneider)

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Phil Mickelson watches his fairway shot on the 14th hole during the third round of the Texas Open golf tournament, Saturday, March 29, 2014, in San Antonio. Mickelson withdrew from the tournament with a pulled muscle. (AP Photo/Eric Gay)