AUSTIN, Texas (AP) Jordan Spieth had another stress-free day in the Dell Match Play, avoiding some of the drama the 18th hole provided Thursday.
So did Jason Day, whose back felt strong enough to drive the first green at 381 yards with a helping wind.
Fifteen matches went the distance at Austin Country Club, and there was no shortage of surprises. Daniel Berger never finished against Phil Mickelson when his club hit a rock structure on the way down. Justin Rose and Rickie Fowler escaped with half-points.
It all set the stage for Friday when all but 16 players from the 64-man field leave town. Already, 22 players have been mathematically eliminated.
Spieth again built a big lead and lost only one hole in a 5-and-4 victory over Victor Dubuisson of France. He has played 30 holes in his two victories, and needs only to halve his match Friday against Justin Thomas to reach the round of 16.
''When you're 3 up and you're striking the ball well on a windy day with a difficult golf course, it's difficult to come from behind,'' Spieth said.
Day ended any suspense about his back injury - first by showing up, then by hitting his opening drive to 12 feet on the 381-yard first hole. He was headed to a 5-and-3 victory over Thongchai Jaidee, which put him in the same position as Spieth.
''If I didn't play today, I was going to pull out of the tournament totally,'' Day said. ''I wasn't going to come back on Friday. I may as well get the rest and recovery and try to get ready for Augusta. I was playing against Thongchai. I felt like if I went there and played some golf, I could get him.
''Fortunately for me, I played some good golf,'' he said. ''There wasn't one shot where I felt it today, which was good.''
Rory McIlroy also got through in a wild match with Smylie Kaufman in which they didn't halve a hole until No. 7. McIlroy won on the 17th hole.
For others, the 18th hole was pivotal.
Mickelson was all square on the last hole when Berger drove left next to a rock structure that forms the 10th tee box. Berger struck the rocks before his club reached the ball. He dropped the club, grabbed his left wrist and looked over to Mickelson to concede the match.
''That's happened to me before, not the injury, but swinging over the top of it or misjudging where the obstacle is,'' Mickelson said. ''It happens. So I was just watching if the ball was struck and it wasn't. He hit the rock on the downswing. And hopefully his wrist is OK.''
Mickelson moves on to a winner-take-all match against Patrick Reed. Berger was among those eliminated and contemplated whether to play Friday, especially with his first Masters appearance only two weeks away.
Sergio Garcia was poised to win his second straight match until Ryan Moore knocked in a 25-foot putt from behind the 17th green to square the match, and then hit wedge to a foot on the final hole for a 1-up victory.
''Match play is just crazy,'' Moore said. ''You just never know what's going to happen.''
Patton Kizzire, one of three PGA Tour rookies in the 64-man field, was 1 down to J.B. Holmes playing the 18th hole when he hit his approach to 5 feet and made it to halve the match. If he missed, he would have been eliminated. Now he can win the group if he beats Emiliano Grillo on Friday and Holmes beats Bubba Watson.
Scott Piercy stayed in the match with Fowler with a remarkable up-and-down from birdie by bouncing a putt across the cart path and rough and onto the green, and winning the 17th when Fowler hit into a hazard. Piercy missed a 10-foot birdie putt on the final hole that would have eliminated Fowler.
Now, there's a mathematical chance for a four-way playoff on Friday to determine who wins the group.
Spieth knows the course better than anyone from his three semesters at Texas - the Longhorns used to stage qualifying on the course. He also faces more attention as the local favorite, not to mention the No. 1 player in the world.
So far, he has played some of his best golf since he won at Kapalua to start the year.
''My swing has been coming around,'' he said. ''I've been working hard on it for the last month or so. Really started showing signs of that work this week.''