AUSTIN, Texas (AP) Jason Day was willing to pull out of the Dell Match Play and rest for the Masters if his back was still hurting Thursday.
All he needed was one swing to know it would be fine.
''When I hit my first tee shot onto the green,'' he said with a smile.
Day took a deep breath, followed by an audible exhale. He swung hard and, with the wind helping, hit drive to 12 feet on the 381-yard opening hole and made the eagle putt. The rest of the day was a breeze, and the 28-year-old Aussie beat Thongchai Jaidee, 5 and 3.
''I was a little bit surprised I was able to come out and hit the shots I did without protecting the golf swing,'' Day said.
His back seized up on the 15th hole Wednesday, and he grimaced and grabbed it on the next hole.
It's not the first time this has happened. Day had to pull out of the BMW Championship in 2014 when his back locked up because of a bulging disc. With a combination of therapy, the right exercises and good sleep, he decided to give it a shot. It helped having one of the late tee times.
He warmed up gingerly, and then began to go full speed on the practice range.
''I was trying to my shots really hard on the range ... just to see how my back would react,'' he said. ''The biggest hurdle was to get through the warm-up. Once I got on the golf course, I forgot about it.''
He looked like the player who won the Arnold Palmer Invitational, and whose game appears to be peaking just in time for Augusta National. Day won the opening two holes with an eagle and Thongchai hitting his next tee shot into the hazard, and then he poured it on with three straight birdies around the turn to seize control.
Day is undefeated in his group. At the very worst, he is assured of being in a sudden-death playoff with Thongchai on Friday, but only if the Thai wins and Day loses against their opponents.
This could be a long week depending on how far he goes. Then again, Day said back issues can creep up without warning.
''I was so disappointed and so angry last night that I was injured because I have been doing the right things,'' Day said. ''I have been doing the right things with my body. These things just pop out of the blue and you can't do anything about it. It's so frustrating because I am playing really good golf right now.
''I know that if I can keep playing this way, I can win.''
Day has talked about exchanging text messages with Tiger Woods about all things golf. In this case, there wasn't time or need to text with Woods, who hasn't played since August because of two back surgeries.
''I'm 28. I don't know how long he's had back issues, but I've had back issues since I was 13,'' Day said. ''So I think I've got him there.''