Phoenix Open leader Phil Mickelson believes that his double bogey on the last hole will help him to "refocus" following two good rounds in Arizona.
The 42-year-old shot a 65 to go with his 60 on day one, leaving him on 17-under par for the tournament.
Mickelson is four clear of Bill Haas, who leads the chase, but said that he is aware of how easily things can change at the top of the leaderboard.
"Unfortunately, I made a double on the last hole and didn't finish the way I wanted to," said Mickelson. "But I think it's a good example of what can happen on this course.
"You can make a lot of birdies and eagles, make up a lot of ground, but there's a lot of water and trouble there that if you misstep you can easily make bogeys and double.
"I think it's very possible that [the double bogey is] going to help me because it's got me refocused, that I cannot ease up on a single shot. I've got to be really focused. These guys are going to make a lot of birdies and I've got to get after it and cannot make those kinds of mistakes."
The double bogey saw Mickelson miss out on a record score for 36 holes.