Phil Mickelson withdrew from the Texas Open after 10 holes Saturday because of what his caddie described as a muscle injury in his side, not his back.
Mickelson was 1-over par for the third round when the three-time Masters champion was taken off the golf course in a cart. His caddie, Jim Mackay said Mickelson felt a twinge on his opening tee shot and that the pain wasn't going away.
He said Mickelson was headed home to San Diego to get it checked out. Mickelson is entered in the Houston Open next week, the last tournament before the Masters.
It's the second time this year Mickelson has withdrawn in the middle of a tournament. He pulled out of Torrey Pines after making the cut because of a back injury.