Marana - World number seven Rory McIlroy tumbled out of the WGC-Accenture Match Play Championship on Thursday when he was pummelled 8&7 by American Ben Crane in the second round.
Irishman McIlroy, who reached the last eight on his debut at Dove Mountain two years ago, succumbed to the second-heaviest defeat ever in the elite 64-man event.
Crane, ranked 38th, birdied three of the first six holes to go four up before sealing victory at the par-five 11th where McIlroy pushed his tee shot well right into the desert scrub.
"Rory didn't have his best day and things were all going in my favour," Crane told reporters after recording seven birdies, two of them conceded, in 11 holes at Dove Mountain's Ritz-Carlton Golf Club.
"I got up and down from some crazy spots. I played exceptional today-- it was one of the best rounds I've ever played."
Crane's victory margin of 8&7 had been previously been achieved twice at the event.
Three-times champion Tiger Woods holds the record for the heaviest win, having hammered Canadian Stephen Ames 9&8 in the first round in 2006.
In other early matches on Thursday, South Korean Yang Yong-eun upset veteran American Stewart Cink 4&3 while U.S. Open champion Graeme McDowell of Northern Ireland beat Englishman Ross Fisher 4&2.
Cink, who eliminated defending champion Ian Poulter of Britain over 19 holes in the opening round, never led against Yang who sealed victory with a five-foot birdie putt on the 15th green.
"Stewart didn't start off very well," Yang said, referring to Cink's tee shot at the par-four first which ended up out-of-bounds on the right. "So I changed my tactics.
"I just tried to pace myself and see what Stewart would do. I played a little defensive and a little conservative compared to the other times I have played match play.
"And I think Stewart had an off-day today, so I just maintained my conservative play, and it fared quite well."
Australian Jason Day pulled off yet another upset in the unpredictable matchplay format by beating Britain's Paul Casey 4&2.
Englishman Casey has reached the final here for the last two years but he was outplayed by the Australian who piled up six birdies and one bogey in bright desert sunshine.
Among the late matches, fourth seed Phil Mickelson appeared to be on the way out, trailing fellow American Rickie Fowler by five with six holes to play.