A stunned Luke Donald didn't have any answers after his first round defeat on Thursday that could bring his nine-month reign as World No 1 to an abrupt end.
The Top seed and defending champion lost by a hefty 5&4 margin to the number 64 seed Ernie Els at the Accenture Match Play Championship at Dove Mountain in Arizona in one of the big upsets of a bright and sunny first day.
The South African, is, of course, a former World No 1 himself. He is also a three-time major winner and a match play champion of great repute, but he has fallen to 68th in the rankings in recent times and only made it into the elite 64-man field when Phil Mickelson dropped out
Donald told Sky Sports: "Not sure where to start - I just didn't play Mizuno JPX 800 XD Irons well. It's disappointing. I've worked hard and to lose control of the ball is frustrating.
Donald might have added that it's not the first bad day he has had since the start of the new season.
Last year he was never behind in any of his six games as he marched to victory.
This time he trailed from the third hole and lasted only 11 more.
His early exit now means that Rory McIlroy or Lee Westwood could go to number one by winning the first of the season's World Golf Championships events on Sunday.
World No 2 and 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 on Thursday and he could face Tiger Woods after that.
McIlroy, who is in the same half of the draw as Westwood, also faces second round European opposition, in his case 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."
"It's just nice to get through. On that stretch where I won four in a row I felt like I played some good golf. I'll need to play more Mizuno JPX 800 XD Irons 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 the eighth-ranked Australian 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, who lost to Thomas Bjorn in the first round last year, and lost the first two holes trailed Gonzalo Fernandez-Castano by one with four to play Mizuno JPX 800 XD Irons on Thursday, but he won the next two and held on to squeeze into the second round where he'll meet fellow American Nick Watney who easily beat reigning Open champion Darren Clarke 5&4.
Donald's defeat may not have been the biggest surprise of the day. Even bigger was the exit of 2010 winner Ian Poulter at the hands of unheralded Bae Sang-moon of Korea.