World Golf Championships-American Express Championship: Picked up his fourth World Golf Championships-American Express Championship victory by coming from two strokes back and defeating John Daly in a two-hole playoff at Harding Park GC in San Francisco. Won for the 10th time in 19 World Golf Championships starts and improved his career playoff record to 8-1. The win was his ninth in California.
Surgery: Pulled out of next two PGA TOUR starts, the Genesis Open and The Honda Classic. Released statement: "My doctors have advised me not to play the next two weeks, to continue my treatment and to let my back calm down. This is not what I was hoping for or expecting. I am extremely disappointed to miss the Genesis Open, a tournament that benefits my foundation, and The Honda Classic, my hometown event. I would like to thank Genesis for their support, and I know we will have an outstanding week." In April, announced on his website he had undergone further back surgery. The operation was performed by Dr. Richard Guyer of the Center for Disc Replacement at the Texas Back Institute.