Luke Donald baffled by 'bad day'

Top seed and defending champion at the Accenture Match Play Championship in Tucson, Donald lost by a crushing 5&4 margin to Ernie Els.

The South African, of course, is a former number one himself and a three-time major winner, but he has fallen to 68th in the rankings and knew he was playing this week only when Phil Mickelson decided to miss the event.

Donald told Sky Sports: "Not sure where to start - I just didn't play well. It's disappointing. I've worked hard and to lose control of the ball is frustrating.

"I felt pretty good about where I was and I'm not sure what happened. Hopefully just one of those bad days."

Last year he was never behind in any of his six games. This time he trailed from the third hole and lasted only 11 more.

Losing means that Rory McIlroy or Lee Westwood could go to number one by winning the first of the season's world championships on Sunday.

Second seed McIlroy came from behind at the turn to beat South African George Coetzee while Westwood, who lost top spot to Martin Kaymer at this event last year, was an impressive six under par in overcoming Belgian Nicolas Colsaerts.

The Worksop golfer will reach the third round for the first time in 12 attempts if he beats Swede Robert Karlsson today - it could be Tiger Woods after that - while McIlroy, who is in the same half of the draw, also has European opposition in Dane Anders Hansen.

On his record, Westwood said: "You can't cruise your way into the tournament, as I do in a lot of them."

McIlroy said: "Obviously it's another incentive knowing that if you win, at the end of the week you could be world number one.

"It's just nice to get through. That stretch (on the back nine) where I won four in a row felt like I played some good golf. I'll need to play more of that tomorrow against Anders."

Three of the sport's top 10 are already out. Italian teenager Matteo Manassero knocked out sixth-ranked Webb Simpson and England's Robert Rock, conqueror of Woods and the world top four in Abu Dhabi last month, got the better of eighth-ranked Adam Scott.

Like Rock, Scots Paul Lawrie and Martin Laird won on the last against Justin Rose and Alvaro Quiros respectively. They now play Ryo Ishikawa and Manassero, while Rock is up against American Mark Wilson.

Woods lost to Thomas Bjorn in the first round last year and trailed Gonzalo Fernandez-Castano by one with four to play, but won the next two and held on - just.

"I've got to hit the ball a little better - and I'll certainly do that," he said before taking on fellow American Nick Watney, an easy 5&4 winner over Open champion Darren Clarke.

Donald's defeat was the biggest surprise, but 2010 winner Ian Poulter also went out to Korea's Bae Sang-moon.