Arizona - Top-ranked defending champion Luke Donald was hammered by Ernie Els on Wednesday while Tiger Woods had a narrow first-round escape at the World Golf Championships Match Play Championship.
South Africa's Els dumped the Englishman 5-and-4, only the third time in event history the top seed has been ousted in the opening round. Els won five of seven holes from the eighth to close out the match on the 14th hole.
"I was trying to just take it as a first round match," Els said. "There's always hype when the No 1 player is playing with the No 64 seed but I think Luke and I took it for what it was.
"Obviously I can play a little bit of golf so I'm sure he didn't really want to face me. But that's the way it worked out. I played well. Luke had a bit of an off day and I'm obviously very pleased to go through."
Former World No 1 Woods survived a scare before progressing through to the second day at the $8.5 million event.
Despite losing the opening two holes, Woods clawed his way back against unheralded Spanish World No 48 Gonzalo Fernandez-Castano to win 1-up and set up a second-round match with fellow American Nick Watney.
Donald was left to lament one of his poorer days out on the golf course. His four bogeys left him hung out to dry.
The result also means he could lose his status as World No 1 should No 2 Rory McIlroy of Northern Ireland or No 3 Lee Westwood of England go deep into the event. Both had reasonably comfortable first round victories.
"It's disappointing," Donald said.
"To lose control of the golf ball like I did today(Wednesday) is really frustrating.
"I don't think it would have mattered who I played today(Wednesday). I gave away too many holes and made too many mistakes. You can't do that in match play against anyone, let alone Ernie."
McIlroy didn't hold back when asked about the chance to arrest the top spot in the world after his 2-up win over South African George Coetzee.
"To be honest, I came in here on Tuesday and talked about if I play well and just win matches that will take care of itself," he said.
"But obviously it's another incentive waking up each morning and knowing that if you win your match at the end of the week you could be World No 1.
"We'll see what happens. I have to get through a lot of matches before that, but it definitely gives me an added incentive this week."
Facing a potential first-round elimination at the event for just the third time in his career, Woods won two of the last four holes and made a clutch up and down from a bunker on the 18th to seal the victory.
"I don't think either one of us had our best stuff on Wednesday," Woods said. "We both made our share of mistakes. There's no doubt about that. But somehow I was able to move on."
Fernando-Castano was left to rue a great chance at victory.
"If there was one day to beat Tiger Woods, this was it," he lamented. "I didn't take the opportunity."
Top seeds in the other brackets moved on without much hassle.
Westwood had no trouble dismissing Belgium's Nicolas Colsaerts 3-and-1 and Germany's Martin Kaymer had an easier day out against Australian Greg Chalmers, triumphing 4-and-2.
Japanese superstar Ryo Ishikawa pulled off a miraculous comeback to upset last week's US PGA winner, Bill Haas.
Ishikawa, seeded 54th, was three down with five holes to play but won four of the final five holes, three with birdies, to take out the 11th seeded Haas 1-up.
"Through the first 13 holes, it had been really tough and I wasn't playing that well," Ishikawa said. "But the last five holes, I was able to compete."
In other upsets, 57th seeded Englishman Robert Rock took down eighth seed Adam Scott 1-up, 53rd-seeded South Korean Y.E. Yang took care of Northern Ireland's 12th-seeded Graeme McDowell 2 and 1 and 19-year-old Matteo Manassero, the 59th seed from Italy, took down US sixth seed Webb Simpson 3 and 2.
Results from Wednesday's first-round matches at the $8.5 million World Golf Championships Accenture Match Play Championship:
Ernie Els (RSA x16) bt Luke Donald (ENG x1) 5 and 4
Peter Hanson (SWE x9) bt Jason Dufner (USA x8) 2 and 1
Kyle Stanley (USA x13) bt K.J. Choi (KOR x4) 2 and 1
Brandt Snedeker (USA x5) bt Retief Goosen (RSA x12) 21 holes
Robert Rock (USA x15) bt Adam Scott (AUS x2) 1 up
Mark Wilson (USA x10) bt Bo Van Pelt (USA x7) 3 and 2
Dustin Johnson (USA x3) bt Jim Furyk (USA x14) 20 holes
Francesco Molinari (ITA x11) bt Thomas Bjorn (DEN x6) 20 holes
Martin Kaymer (GER x1) bt Greg Chalmers (AUS x16) 4 and 2
David Toms (USA x8) bt Rickie Fowler (USA x9) 1 up
Matt Kuchar (USA x4) bt Jonathan Byrd (USA x13) 1 up
Bubba Watson (USA x5) bt Ben Crane (USA x12) 3 and 2
Steve Stricker (USA x2) bt Kevin Na (USA x15) 2 and 1
Louis Oosthuizen (RSA x7) bt Aaron Baddeley (AUS x10) 2 and 1
Y.E. Yang (KOR x14) bt Graeme McDowell (NIR x3) 2 and 1
Hunter Mahan (USA x6) bt Zach Johnson (USA x11) 19 holes
Rory McIlroy (NIR x1) bt George Coetzee (RSA x16) 2 up
Anders Hansen (DEN x9) bt Kyung-Tae Kim (KOR x8) 5 and 3
Miguel Angel Jimenez (ESP x13) bt Sergio Garcia (ESP x4) 2 and 1
Keegan Bradley (USA x5) bt Geoff Ogilvy (AUS x12) 4 and 3
Jason Day (AUS x2) bt Rafael Cabrera-Bello (ESP x15) 19 holes
John Senden (AUS x10) bt Simon Dyson (ENG x7) 4 and 3
Charl Schwartzel (RSA x3) bt Gary Woodland (USA x14) 4 and 2
Bae Sang-Moon (KOR x11) bt Ian Poulter (ENG x6) 4 and 3
Lee Westwood (ENG x1) bt Nicolas Colsaerts (BEL x16) 3 and 1
Robert Karlsson (SWE x8) bt Fredrik Jacobson (SWE x9) 6 and 5
Nick Watney (USA x4) bt Darren Clarke (NIR x13) 5 and 4
Tiger Woods (USA x5) bt Gonzalo Fernandez-Castano (ESP x12) 1 up
Matteo Manassero (ITA x15) bt Webb Simpson (USA x2) 3 and 2
Martin Laird (SCO x10) bt Alvaro Quiros (ESP x7) 1 up
Ryo Ishikawa (JPN x14) bt Bill Haas (USA x3) 1 up
Paul Lawrie (SCO x11) bt Justin Rose (ENG x6) 1 up