MARANA, Ariz. -- The most fickle part of the Match Play Championship for Louis Oosthuizen was his nagging back injury.
His luck ran out Saturday when he felt pain in his back while warming up on the range. When he first tried to hit a draw on the par-5 second hole, it got even worse. And one point, he was on his back on the 13th tee as his trainer tried to stretch him out.
"It's a bit painful that it always happens when I'm playing well," Oosthuizen said after losing on the 17th hole to Jason Day.
He was playing well enough that Oosthuizen required only 47 holes to reach the quarterfinals, the fewest of anyone. But it was a battle from the start, especially against a player like Day who has reached the semifinals the last two years.
Oosthuizen pulled off an unlikely birdie on the second hole to square the match, and he went ahead on the third with a 25-foot birdie putt. Day was able to at least try to drive the par-4 fourth green to set up a birdie, while Oosthuizen chose to lay back. Day won the hole and never trailed again.
"If I can commit myself to hit the shot, it's not that bad," Oosthuizen said. "But I can't commit. My body is restricting me to go through the shot."
Oosthuizen needs to get his back sorted out. He's been dealing with it since last summer. Some weeks it feels good, other weeks not so much. He said it most affects him when he plays a long stretch of golf.
And this has been a long week.
"I'm glad to not be playing tomorrow," he said with a smile. "I don't want to be the first guy to withdraw from the finals or semifinals."
Oosthuizen is scheduled to play the Honda Classic next week ahead of the next World Golf Championship at Doral. He said he would see how he feels in a couple of days, and might end up dropping Honda and adding the week after Doral at Innisbrook.