The first day of match play teed off Wednesday morning at the Austin Country Club.
The Dell Match Play Championships has a format that guarantees every golfer to play three rounds, with the winner of 16 groups of four advancing to weekend play.
Tiger Woods started with a win on the first hole.
Jordan Spieth started slowly, falling behind three to Billy Horschel.
But Spieth came back to get a tie.
Phi Mickelson wasn't as lucky. He hit one out of bounds on number 17 and that proved to be his last hole as he lost to Henrik Stenson.
Mickelson is in a tough group that also includes Jason Day and Jim Furyk.
Furyk beat Day 2 up, putting Day and Mickelson in a hole as they head to day two on Thursday.
The field will narrow to 16 golfers on Saturday morning. The quarterfinals will take place Saturday afternoon.
The final four golfers will be in the semi-finals Sunday morning, followed by Sunday afternoon's championship match.
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