By Mark Lamport-Stokes
MARANA, Arizona (Reuters) - Top seed and defending champion Luke Donald crashed out of the WGC-Accenture Match Play Championship on Wednesday, losing 5&4 to late-entry Ernie Els in the opening round.
The triple major champion 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 told reporters. "I just didn't play very well. It's disappointing. I've been working really hard.
"I struggled. 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.
While three-times winner Tiger Woods scraped through one up against Gonzalo Fernandez-Castano, Charl Schwartzel and Bae Sang-moon both 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.
British world number three Lee Westwood beat Belgian Nicolas Colsaerts 3&1 and fourth-ranked German Martin Kaymer advanced with a 4&2 win over Australian left-hander Greg Chalmers.
Woods, winner of this event in 2003, 2004 and 2008, was two down to Fernandez-Castano after just two holes but finally ended a wildly fluctuating encounter with an eight-foot par putt at the 18th.
"We both made our share of mistakes, there's no doubt about that, but somehow I was able to move on," Woods said.
In other first-round matches, in-form South Korean Yang Yong-eun beat Britain's Graeme McDowell 2&1 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 in the first match out.
"I ran into a man that 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.
"I made six birdies today. You just run into the wrong guy on the wrong day, and you have got your work cut out. I didn't take care of business, so I'm disappointed, yeah."
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 on a breezy, sun-splashed day in the Arizona desert.
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.
(Reporting by Mark Lamport-Stokes; Editing by Frank Pingue)