Jason Day has been exchanging text messages with Tiger Woods on all things golf, so perhaps he could lean on Woods for his latest issue.

A bad back.

Day never saw it coming in the Dell Match Play. One minute he was tapping in for par to keep his 3-up lead over Graeme McDowell, and a minute later he was reaching toward his lower back. The pain was far more obvious on his tee shot at the 16th when Day let the driver fall from his hands as he grabbed his back and grimaced. He climbed gingerly into a bunker, and grabbed his thighs and took a knee as the match was ending.

What's next? Good question.

Day headed to the fitness trailer for treatment and left without speaking to reporters.

His agent issued a statement later that essentially said the sun rises in the east. He said Day tweaked his back on the 15th hole and had work done. He was happy with the outcome of his match. And that he's getting prepared to play on Thursday.

Day did tell the Australian Associated Press as he headed for treatment that he felt "searing pain" in both sides of his lower back.

That figures to be the center of attention Thursday for the second round of group play at Austin Country Club.

BAD TIMING: Day at least was in control of his match when his back began to act up. He scratched out a par on the 16th hole and won his match, 3 and 2. The fact the Masters is only two weeks away is troublesome for Day, especially coming off a victory in the Arnold Palmer Invitational.

In this round-robin format, at least the 28-year-old Aussie has options.

He faces Thongchai Jaidee, a winner over Paul Casey. Day could concede Thursday's match against Thongchai to rest and then play Friday. That would mean Thongchai has a 2-0 record in group play, and Day would have to beat Casey and hope Thongchai loses to McDowell on Friday to force a playoff to decide who wins the group.

Odds are he will play.

THE LOCAL FAVORITE: Jordan Spieth had the biggest crowd as a Texas Longhorns alum, and he gave them what they wanted to see. Spieth raced out to a 4-up lead over Jamie Donaldson and wound up winning on the 16th hole.

"I felt like everybody was on our side today," Spieth said. "I almost felt like a home Ryder Cup match. And Jamie, I'm not sure what he would say about it. ... Everyone was very respectful, but every single step I took, somebody was yelling at you, 'Hook 'Em Horns' or 'Go Jordan, we're rooting for you.' Which is really, really cool."

Next up is Victor Dubuisson of France, the finalist in 2014 and a winner over Justin Thomas in the opening round at Austin.

THE GREAT ESCAPE: Rory McIlroy won all seven of his matches when he won the Match Play last year in San Francisco.

That streak nearly ended Wednesday. McIlroy never led, and it appeared he would go 1 down with two holes to play until Thorbjorn Olesen missed a 3-foot putt on the 16th hole. And then the Dane delivered an even greater shock.

They were all square playing the 18th when Olesen shanked a chip that effectively handed McIlroy the match.

"Match Play is all about getting through," McIlroy said.

His next job is to get through Smylie Kaufman.

ON THE ROPES: Rickie Fowler was the highest seed (No. 5) to lose in the opening round. That's not the end of his week because of the round-robin format.

But it doesn't make it any easier.

Fowler will be eliminated if he doesn't beat Scott Piercy on Thursday. If that happens, Fowler will have to return Friday to play a meaningless match (for him). A year ago, Fowler already clinched a spot in the round of 16 and had to play a meaningless match Friday, but at least knowing he was advancing instead of going home.

Fowler wasn't alone. Of the top 16 seeds, Dustin Johnson, Jimmy Walker and Hideki Matsuyama all lost and face must-win matches Friday.

A year ago, only three players who lost in the opening round advanced to the weekend. Halved matches are allowed in group play this year, so that would help the likes of Adam Scott and Bubba Watson, even though both felt they should have won their matches.

SHOT OF THE DAY: There wasn't many, given the blustery conditions and difficulty of the contoured greens. Martin Kaymer should get some credit for being 1 up against Shane Lowry and hitting driver on the 376-yard 18th hole (downwind) onto the green for a two-putt birdie and the win.