Tiger Woods advanced to the second round of the World Golf Championships Match-Play Championship on Wednesday with a 1-up first-round victory over Spain's Gonzalo Fernandez-Castano.
Top seed Luke Donald crashed out of the championship losing 5&4 to late entry Ernie Els.
Once again the elite World Golf Championships event lived up to its reputation for wild unpredictability and there were 15 upsets from the 32 matches at Dove Mountain's Ritz-Carlton Golf Club.
Donald won last year's title with an imperious display, never trailing in any of his six matches, but he struggled against South African Els on a sun-splashed day in the Arizona desert where the heavily contoured greens ran fast and firm.
Fifth seed Woods, who was eliminated in the first round last year, ousted the 12th-seeded Spaniard to book a second-round match Thursday against US fourth seed Nick Watney, a 5-and-4 winner over Northern Irishman Darren Clarke.
"We had some big (momentum) swings," Woods said. "I'm very fortunate to move on."
Former World No. 1 Woods, a 14-time Major winner, has not won a US PGA title since September of 2009 as he struggled with injuries and the aftermath of his infamous sex scandal, but Woods is a three-time champion of this tournament.
Fernandez-Castano birdied the first two holes to seize a 2-up edge on Woods, who answered with a par to win the fifth hole and birdies at the par-4 seventh and par-5 eighth to stand 1-up at the turn.
Woods took a double bogey after a bad tee shot at the par-4 10th, allowing the Spaniard to level the match despite a bogey, and Woods made bogey at the par-5 11th while Fernandez-Castano birdied to seize a 1-up lead.
After stopping the skid with a clutch par putt at the 12th, Woods fought back over the final holes.
Woods squared the match with a birdie at the par-4 15th and took the lead with a par at the par-3 16th. Both made par at the par-4 17th and par-4 18th, allowing Woods to improve to 10-2 in first-round matches at the event.
But an ill omen for Woods was his difficulty in reading the greens over the Dove Mountain course. Woods has struggled with his putting as he tries to regain the form that made him a global sensation.
"I hit a couple of bad putts but I had a hard time reading these greens," Woods said. "The grain on the greens isn't matching up with the valley.
"I talked myself out of two or three putts where if I had gone with my first instinct I would have made it."
Four other matches in Woods' quarter of the draw, the Sam Snead division, saw upset victories by 14th-seeded Japanese prodigy Ryo Ishikawa and Italian 15th seed Matteo Manassero as well as Scotsmen Martin Laird and Paul Lawrie.
Triple Major winner Els made the most of an error-prone performance by the British world number one and sealed victory when he sank a 10-foot birdie putt at the par-four 14th.
"I'm not sure where to start," a subdued Donald, who became only the third top seed to lose in the event's opening round, told reporters. "I just didn't play very well. It's disappointing.
"I gave away too many holes and made too many mistakes. You can't do that in match play against anyone, let alone Ernie."
The lowest-ranked player in the elite field of 64, former world number one Els was gifted a spot at Dove Mountain when Phil Mickelson withdrew to spend time with his family.
"There's always hype when the No. 1 player is playing the No. 64 seed," said Els. "But Luke and I took it for what it was.
"I think he didn't want to play me and I sure as hell didn't want to play him in the first round, but that's the way it worked out."
Charl Schwartzel and Bae Sang-moon won their opening matches in comfort.
Masters champion Schwartzel of South Africa eased past big-hitting American Gary Woodland 4&2 and South Korean Bae upset Britain's Ian Poulter, the 2010 champion, 4&3.
Northern Ireland's Rory McIlroy survived a late wobble to beat South African George Coetzee two up, Lee Westwood beat Belgian Nicolas Colsaerts 3&1 and German Martin Kaymer advanced with a 4&2 win over Australian left-hander Greg Chalmers.
Earlier, South Korean Yang Yong-eun beat Graeme McDowell 2&1 in a match of high quality and Dustin Johnson scraped past fellow American Jim Furyk after 20 holes.
Yang, who became the first Asian male to win a Major with his victory at the 2009 PGA Championship, produced sizzling form with seven birdies.
"I ran into a man who played extremely well," a frustrated McDowell said. "I felt like I had to follow him all day long, and I did most of the day, but he didn't put a foot wrong."
Soon after Yang's win, Japan's Ryo Ishikawa came from three down after 13 holes to beat American Bill Haas one up before Paul Lawrie edged fellow Briton Justin Rose by the same margin.
Ishikawa birdied 14, 15 and 17 before wrapping up victory on the 18th green against an in-form opponent who won the PGA Tour's Northern Trust Open on Sunday in a playoff.
"Through the first 13 holes, it was really tough and I wasn't playing that well," Ishikawa said through an interpreter. "But the last five holes, I was able to compete with the opponent. This course is suited for me."
In other matches, Hunter Mahan battled past fellow American Zach Johnson after 19 holes and Italian Matteo Manassero never trailed on his way to a 3&2 win over American Webb Simpson.