Mickelson withdrew after pulling the muscle teeing off on No. 1 his 10th hole of the round. He hopes to play next week in the Houston Open, the last event before the Masters.
"I pulled a muscle on my downswing trying to hit it hard," Mickelson said a statement. "It just killed and it wouldn't subside for 10 or 12 seconds. I'm going back to San Diego (for) a couple of days and have a doctor look at it, but there's really not much you can do for a pulled muscle. I hope I'll be OK to play the Shell in Houston, but I just don't know."
Lefty was 1-over par in the round and 4 over overall when the three-time Masters champion was taken off the course in a cart. His caddie, Jim Mackay, said Mickelson felt a twinge on his tee shot on No. 1.
Carlsbad, Calif. • Cristie Kerr made a 55-foot par-saving putt after hitting her final approach into the water, giving her a share of the lead with Lizette Salas after the third round of the Kia Classic.
Kerr finished with a 2-under 70 to match Salas at 10-under 206 at Aviara. After dropping a stroke on the par-5 17th, Kerr holed out from the edge of the green on the par-4 18th after taking a penalty drop.
Salas, the former Southern California player from Azusa, had a 69. She birdied the par-5 17th for a share of the lead and matched Kerr with a par on the last
Kerr won the Kingsmill Championship last year for her 16th LPGA Tour title.
Dori Carter, the second-round leader after a course-record 64, had a 74 to drop into a tie for third at 8 under with Thailand winner Anna Nordqvist, Ayako Uehara and Shanshan Feng.
Nordqvist and Uehara shot 67, and Feng had a 69. Third-ranked Stacy Lewis was 7 under after a 73.
Steven Bowditch -12
Matt Kuchar -9
Andrew Loupe -9
Pat Perez -8
Kevin Na -7
Chad Collins -6
Daniel Summerhays -6