Jason Day shrugged off his back problems to win for a second time at the Dell Matchplay in Texas today to give himself a good chance of qualifying for the top 16 of the World Golf Championship event.
Day, who had suffered spasms after his first-round win, was in some doubt for today's match against Thongchai Jaidee of Thailand, even up to the point where he hit the driving range.
But the Australian dominated the match, winning five and three.
If Day beats the 23rd-seeded Paul Casey of England tomorrow he will advance to the knockout stage.
The world No. 2 hit every shot hard on the range to test his back, and went through rigorous stretching exercises both before and during his match, but came through fine.
"It's not too bad,'' he said. "Yesterday it was definitely sore. I mean, I've had it before. I know what the protocols are for me when these things pop up. It's a disc, when it gets inflamed the facet joints lock up and then everything goes into spasm and I can't move and it's really difficult to play golf.''
Day can reach a world No. 1 ranking this week if he advances further than the current No. 1, American Jordan Spieth, who is unbeaten in two matches so far.
The other Australian still in the running is Adam Scott, who needs to beat American Bill Haas tomorrow to reach weekend play. Scott defeated England's Chris Wood today, three and two.
Marc Leishman, Marcus Fraser and Matt Jones are all eliminated from the top 16 who will play on the weekend.
Leishman lost to Lee Westwood today, Jones was beaten by England's Andy Sullivan and Fraser halved his match with Shane Lowry of Ireland.