Tiger Woods’ bid for the Accenture Match Play Championship title has barely survived after a tight encounter at Dove Mountain.
Top seed Woods was given a fright by Australian Aaron Baddeley, before winning their third-round match one-up at the second extra hole.
Meanwhile, 59th seed Colin Montgomerie struggled to make a putt down the stretch as his fairytale run ended against American Stewart Cink.
They were all square at the turn, but Cink took the lead for good with a birdie at the par-five 10th and pulled away, rolling in a 15-footer at the 16th hole to deliver the final blow, winning emphatically four and two.
"Sometimes you can't explain golf," said Cink. I didn't really feel I had control of my ball today off the tee and I think Colin would agree with that.
"It was ugly but I scrambled my rear end off and made a lot of good putts.
"Sometimes when you're hitting it all over the place and recovering well and making a few putts, it's demoralising to your opponent, and I think that's what happened."
Montgomerie certainly sounded demoralized as he blamed his exit on mediocre putting, and said: "I had chances on 10, 11, 12, 13, 14, 15 and 16 and missed them all.
"He putted very well. He even said he got lucky on a few of his putts and I was unlucky."
Paul Casey trailed all the way in his game, but at least made a match of it, extending KJ Choi to the very end before the Korean prevailed two-up.
The only European through to the quarter-finals is defending champion Henrik Stenson, who survived another tight battle.
Less than 24 hours after being taken to seven extra holes, Stenson got the job done in regulation, but only just, edging American Jonathan Byrd by one.
Stenson has won all three of his matches by the narrowest of margins and admitted: "I've managed to get out of a few situations Houdini-style.
The Swede earned a quarter-final match against American Woody Austin, who was too good for compatriot Boo Weekley, winning four and two.
In another match, Angel Cabrera, the US Open champion from Argentina, used his prodigious power to give American Steve Stricker a four-and-three hiding in the World Golf Championships event.
American Justin Leonard beat Australian Stuart Appleby three and two, while Fiji's Vijay Singh beat Australian Rod Pampling one-up at the seventh extra hole.
In Saturday's quarter-finals, Woods plays Choi, Stenson meets Austin, Leonard duels with Singh and Cabrera meets Cink.