Poulter had his chances to win but his defence of the title ended in the first round
England's Ian Poulter has become the first defending champion in nine years to go out in the first round of the WGC Match Play Championship.
Poulter did not trail until opponent Stewart Cink holed a four-foot birdie putt on the first extra hole after the match had finished level.
Tiger Woods also made a quick exit at Dove Mountain, Arizona, losing to Denmark's Thomas Bjorn.
Lee Westwood, however, progressed after the Englishman beat Henrik Stenson.
Westwood's compatriots Luke Donald and Justin Rose also went through, as did Northern Ireland duo Rory McIlroy and Graeme McDowell.
McIlroy defeated Jonathan Byrd 4&2, while US Open champion McDowell beat American Heath Slocum 4&3. But Scotland's Martin Laird was beaten by Italy's Edoardo Molinari.
Rickie Fowler set up a mouth-watering second-round tie against Ryder Cup team-mate Phil Mickelson after the young American defeated Sweden's Peter Hanson. Former world number one Mickelson beat Australia's Brendan Jones 6&5.
He putted me off the golf course. That's what you have to do in this format
The 35-year-old Poulter, who had voiced his displeasure at his early tee-time, will rue a missed putt to win the match on the 18th. The last defending champion to lose in the first round was Steve Stricker in 2002 at La Costa.
"I really should have shut the match out, to be honest with you," said Poulter.
"He putted me off the golf course. That's what you have to do in this format. I did it last year and managed to go all the way.
"I missed my chances and therefore I've been punished."
Woods could not hide his frustration after a defeat which could result in him falling as far as eighth on the rankings come Sunday night.
Moments after he made an eight-foot birdie putt on the 18th hole to extend the match, he hit a three wood to the right and the ball landed in a desert bush.
After taking two shots to recover from the error, he conceded an 18-foot bogey putt.
Woods's round was littered with costly errors
It was only the second time that Woods, the No. 3 seed, had been eliminated in the first round.
He will try again at another World Championship in Miami in a fortnight, but after finishes of 44th and 20th in his first two starts this season the longest barren spell of his life has now reached 18 tournaments.
"Disappointing, very disappointing. I had a chance. I had all the momentum going down 18 and just gave it away," he said.
"It's easy to put the ball in the fairway and I couldn't even do that."
Dane Bjorn, however, believes Woods is getting closer to rediscovering his best form.
"There's a way back for him - and he'll get there.
"He's not playing his absolute best, but there were a lot of good swings. His driving was a lot better than it's been. He's taking strides."
I played really well. I achieved a victory against one of the best players in the world and a past champion
Matteo Manassero on his win over Steve Stricker
World number eight Steve Stricker was stunned by 17-year-old Italian Matteo Manassero 2&1.
Stricker, 43, had been one up on Manassero after nine holes but made a surprising exit from the tournament when the teenager rolled in a 21-foot birdie putt at the 17th.
"It's a big achievement for me," said Manassero, the youngest player ever to compete in the Match Play event.
"I played really well. I achieved a victory against one of the best players in the world and a past champion."
Meanwhile, Donald was an easy 6&5 winner against Charley Hoffman of the US and will now face Molinari.
"I don't think Charley was in his best form," admitted ninth-seed Donald after closing out the victory. "It's always nice to win your first match and to win it pretty easily. You always go into matches expecting them to be tough."
In other matches JB Holmes beat Colombia's Camilo Villegas 4&2, Ernie Els came back from three down after three to beat Jeff Overton at the 19th, while Dubai Desert Classic winner Alvaro Quiros went out at the 20th to Korean YE Yang.
Matt Kuchar progressed to the second round after beating Denmark's Anders Hansen in a marathon 22-hole match and Martin Kaymer also moved to the next round after defeating Seung-Yul Noh 7&6.
First-round results (US unless stated)
Stewart Cink bt Ian Poulter (Eng) at the 19th
JB Holmes bt Camilo Villegas (Col) 4&2
Luke Donald (Eng) bt Charley Hoffman 6&5
Edoardo Molinari (Ita) bt Martin Laird (Sco) 3&2
E Els (SA) bt Jeff Overton at the 19th
Graeme McDowell (NI) bt Heath Slocum 4&3
Ross Fisher (Eng) bt Robert Allenby (Aus) 4&3
YE Yang (Kor) bt Alvaro Quiros (Sp) at the 20th
Miguel Angel Jimenez (Spa) bt Yuta Ikeda (Jpn) 2&1
Jason Day (Aus) bt Kyung-tae Kim (Kor) 3&2
Rory McIlroy (NIrl) bt Jonathan Byrd 4&2
Ben Crane by Adam Scott (Aus) 4&2
Paul Casey (Eng) bt Richard Green (Aus) at the 19th
Matteo Manassero (Ita) by Steve Stricker 2&1
Ryan Palmer bt Jim Furyk 2 up
K J Choi (Kor) bt Retief Goosen (SA) 1 up
Phil Mickelson bt Brendan Jones (Aus) 6&5
Robert Karlsson (Swe) bt Hiroyuki Fujita (Jpn) 5&3
Hunter Mahan bt Sean O'Hair 4&3
Martin Kaymer (Ger) bt Seung-yul Noh (Kor) 7&6
Ryan Moore bt Francesco Molinari (Ita) 3&1
Charl Schwartzel (SA) bt Ryo Ishikawa (Jpn) at the 20th
Rickie Fowler bt Peter Hanson (Swe) 1 up
Matt Kuchar (US) bt A Hansen (Den) at the 22nd
Bo Van Pelt bt Louis Oosthuizen (SA) 2 up
Geoff Ogilvy (Aus) bt Padraig Harrington (Irl) 4&3
Mark Wilson bt Dustin Johnson at the 19th
Bubba Watson bt Bill Haas 3&2
Thomas Bjorn (Den) bt Tiger Woods at the 19th
Lee Westwood (Eng) bt Henrik Stenson (Swe) 3&2
Nick Watney bt Anthony Kim 5&4
Justin Rose (Eng) by Zach Johnson 2&1