The top two seeds were eliminated Friday as golf's most unpredictable tournament lived up to its reputation.
Woods, who had won 13 consecutive matches, fell behind early against Nick O'Hern and never caught up. His last hope vanished when he hit into a bunker on the 17th hole, and the lanky lefty from Down Under holed a 25-foot putt for a 3-and-1 victory.
'Nick made all the putts he had to make,' Woods said. 'I didn't make any.'
Singh kept alive his dubious streak of never advancing beyond the second round of the Accenture Match Play Championship. He took a 1-up lead over Jay Haas by driving the 332-yard sixth hole, but the putts kept bumping away from the hole and the 51-year-old Haas pulled away for the 3-and-2 victory.
The 16 winners took a brief break for lunch before playing the third round.
Unlike previous years when top seeds were beaten early, at least La Costa was not deprived of some star power.
Phil Mickelson, the No. 3 seed who is coming off two straight PGA Tour victories, again had an easy time on the course not far from his home. The Masters champion made four straight birdies early in his match and won, 4 and 3, over Angel Cabrera.
U.S. Open champion Retief Goosen, the No. 4 seed, recovered from an early deficit to beat Fred Couples, 1 up.
Sergio Garcia (No. 6) was 2 down through 10 holes, but took advantage of some late mistakes by Jerry Kelly and beat him on the 19th hole to advance to third round.
'It was a tough match,' Garcia said. 'We didn't play too well, but it was exciting. There was a lot of energy around it. I'm glad I went through it, to get my game in a bit of a better shape like I did yesterday.'
Other top-10 seeds advancing were Stewart Cink, who eliminated Ryder Cup captain Tom Lehman, and Davis Love III, who trounced Lee Westwood of England.
Love had the easiest time, making five birdies and being conceded an eagle putt in 13 holes. His margin of victory, 7 and 6, tied the biggest rout at this tournament previously set by six other players.
O'Hern became the latest Aussie to take down Woods in the early stages of the Match Play Championship. Three years ago, Peter O'Malley became the only No. 64 seed to advance when he knocked Woods out in the first round.
Woods won his next 13 matches, resulting in back-to-back titles, but he was no match for a steady O'Hern and his magical touch around the greens.
O'Hern quickly built a 2-up lead, making a 10-foot birdie on No. 2 and a 6-footer on the par-5 third hole. Woods showed early on that putting on the spongy greens at rain-soaked La Costa would be a problem for him. He missed from 3 feet on No. 3, and from 5 feet on the fifth hole to fall 2 down.
And every time he had a putt to pull even, it slid around the edge.
Woods was driving the ball some 40 yards past O'Hern on every hole, but that didn't matter. O'Hern always hit first, and usually put the ball inside Woods.
The Aussie took a 2-up lead at the turn with a 6-iron into 4 feet on the No. 9, the 467-yard hole that again was converted into a par 3. And when he holed a 12-footer at No. 13, O'Hern was 3 up.
The only hole Woods won on the back nine was at No. 15, when O'Hern took four shots to reach the green.
'He doesn't make a lot of mistakes,' Woods said.
O'Hern narrowly survived the first round against Charles Howell III, winning on the 19th hole. He was hardly intimidated playing the two-time defending champion, especially when Woods began catching the lip on his putts.
'Tiger was unfortunate with his putts,' O'Hern said.
But they are the same for everyone, and the Aussie looked comfortable easing his way into the second round.
Mickelson had no problem with the greens. With four straight birdies, he quickly surged ahead of Cabrera, then finished his front nine with two more birdies to for a 4-up lead.
Still, the biggest performance by a lefty at La Costa belonged to O'Hern on Friday. He eliminated Woods, and left the Match Play Championship as wide open as it usually is.
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