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Webb Simpson shot a 6-under 64 on Thursday in his first competitive round at Firestone Country Club to take a one-stroke lead in the Bridgestone Invitational.

The 2012 U.S. Open champion had six birdies in an eight-hole span to get the upper hand on seven-time Bridgestone winner Tiger Woods. Woods, with top-10 finishes in 11 of his 13 starts on the course, shot a 66 in the World Golf Championships event.

Henrik Stenson was alone in second with a 65. Defending champion Keegan Bradley, Ryan Moore and Chris Wood, another first-time entrant, matched Woods at 66.

Phil Mickelson had a 72 in his return from winning the British Open two weeks ago at Muirfield.

The Bridgestone also serves as a tuneup for next week's PGA Championship at Oak Hill.