Phil Mickelson withdrew from the Memorial Tournament on Thursday, shortly after struggling to his worst round at Muirfield Village.
Mickelson carded a seven-over 79, ending his round with five bogeys and a double-bogey in his final seven holes. He cited mental fatigue and poor hitting as reasons he withdrew.
"I have to look at what's best for me to play in the U.S. Open, and I'm going to take the next few days to kind of rest up," Mickelson said.
The U.S. Open, which Mickelson called "a mental and physical grind," is just two weeks away. He said he hasn't had a chance to get to the course -- the Olympic Club in San Francisco -- and may do so in the next week.
Mickelson also withdrew from the Memorial in 2007, and has a spotty record at the tournament, with just two top-five finishes in his previous 12 starts.