Masters champion Jordan Spieth and world number one Rory McIlroy enjoyed comfortable victories on the opening day of the WGC-Cadillac Match Play, as a host of big names were grateful not to be making an early exit.
Spieth defeated Finland's Mikko Ilonen 4 and 2 while McIlroy saw off Jason Dufner 5 and 4, but defending champion Jason Day, Justin Rose, Ian Poulter, Henrik Stenson, Adam Scott and Graeme McDowell all suffered defeats at Harding Park in San Francisco.
That would usually mean heading for the airport and a flight home, but the traditional straight knockout format has been replaced by a round-robin phase with the 64 players divided into 16 groups of four.
"I don't feel very hopeful right now but I have a shot, so I guess that's a good thing," Rose said after losing to Australia's Marc Leishman, just three days after winning the Zurich Classic in his first appearance since finishing second in the Masters.
Leishman, who did not play at Augusta National as his wife recovered from a life-threatening illness, won the opening hole with a birdie and was never behind in the match before sealing a 3 and 2 win.
Poulter also lost the opening hole to a birdie from former US Open champion Webb Simpson, but ultimately paid the price for carding four bogeys in six holes from the third as Simpson gained a measure of revenge for losing to the Englishman in the “Miracle at Medinah” in 2012.
“I’ve drawn him in the last two Ryder Cups and what a match player he is,” Simpson told Sky Sports 4. “He is always tough and even being three or four up I knew I couldn’t let up and I’m happy to get by for sure.”
Poulter later wrote on Twitter: “Truly disgusting putting today, it was actually farcical. Spent 3 hours on the putting green this afternoon. We will see if it helped.”
Stenson thought he had halved his match with John Senden when the Australian birdied the 18th, only to be told extra holes would be played to determine the result, with Senden securing victory with a birdie on the 19th.
Day lost 4 and 3 to American Charley Hoffman, while compatriot Scott declined to speak to reporters after being beaten 5 and 4 by Italy's Francesco Molinari, the same scoreline by which Charl Schwartzel beat last year's runner-up Victor Dubuisson.
Former US Open champion Graeme McDowell lost on the 18th to Shane Lowry, but Ryder Cup team-mate McIlroy only needed to be an approximate one under par in beating Dufner.
“I felt like tee to green I played pretty well,” McIlroy told Sky Sports 4. “I didn’t hole many putts and felt that the green speeds were pretty inconsistent, but did what I needed to do and we move on to tomorrow.”
In the all-European group 10, Sergio Garcia recovered from two down to beat Tommy Fleetwood by two holes, while Jamie Donaldson edged out Austria's Bernd Wiesberger on the 18th.
“He (Fleetwood) played well all day then hit a couple of iffy shots in the last five holes and I was able to take advantage,” Garcia told Sky Sports 4.
Lee Westwood continued his good form after winning in Jakarta on Sunday, beating Matt Every on the 18th, while Danny Willett enjoyed a successful debut in the event with a 3 and 2 win over Ryan Moore.
In the same group, compatriot Andy Sullivan was left to rue several missed chances as he lost 2 and 1 to American Ryder Cup star Patrick Reed.
Two-time Masters champion Bubba Watson enjoyed a comfortable 5 and 4 win over Miguel Angel Jimenez, while Scotland's Stephen Gallacher suffered the biggest defeat of the day, losing 7 and 6 to former champion Hunter Mahan.
Gallacher, who lost both his Ryder Cup matches at Gleneagles, was an approximate three over par and has now lost 11 of his last 12 singles contests in match play.
“It was a combo of me playing well and putting the pressure on him and he did not have his best stuff today,” said Mahan, who beat Rory McIlroy to win the title in 2012 and reached the final again the following year.
Gallacher's fellow Scot Marc Warren had more success, enjoying a 2 and 1 win over world number 12 JB Holmes after seeing an early three-hole lead wiped out by the 15th.
“I kept telling myself a player of that calibre is going to come back at you and he did,” Warren said. “It was just about whether I could counter him and I was really calm and composed.”
Shot of the day had come from American Ben Martin, who fired a hole-in-one on the 17th to take the lead over Matt Kuchar before sealing victory on the last.
FULL RESULTS: ROUND 1
Group 1: Rory McIlroy (N Irl) bt Jason Dufner 5 and 4
Group 1: Billy Horschel bt Brandt Snedeker 5 and 4
Group 2: Jordan Spieth bt Mikko Ilonen (Fin) 4 and 2
Group 2: Lee Westwood (Eng) bt Matt Every 1 up
Group 3: Bill Haas bt Brendon Todd 3 and 2
Group 3: John Senden (Aus) bt Henrik Stenson (Swe) 19 Holes
Group 4: Bubba Watson bt Miguel Angel Jimenez (Spa) 5 and 4
Group 4: Louis Oosthuizen (Rsa) bt Keegan Bradley 6 and 5
Group 5: Jim Furyk bt George Coetzee (Rsa) 3 and 2
Group 5: Martin Kaymer (Ger) bt Thongchai Jaidee (Tha) 3 and 1
Group 6: Marc Leishman (Aus) bt Justin Rose 3 and 2
Group 6: Anirban Lahiri (Ind) bt Ryan Palmer (USA) 4 and 2
Group 7: Charley Hoffman bt Jason Day (Aus) 4 and 3
Group 7: Zach Johnson bt Branden Grace (Rsa) 2 up
Group 8: Charl Schwartzel (Rsa) bt Victor Dubuisson (Fra) 5 and 4
Group 8: Dustin Johnson bt Matt Jones (Aus) 3 and 1
Group 9: Francesco Molinari (Ita) bt Adam Scott (Aus) 5 and 4
Group 9: Paul Casey (Eng) bt Chris Kirk 22 Holes
Group 10: Sergio Garcia (Spa) bt Tommy Fleetwood (Eng) 2 up
Group 10: Jamie Donaldson (Wal) bt Bernd Wiesberger (Aut) 1 up
Group 11: Webb Simpson (USA) bt Ian Poulter 3 and 2
Group 11: Gary Woodland bt Jimmy Walker 19 Holes
Group 12: Marc Warren (Sco) bt J.B. Holmes 2 and 1
Group 12: Brooks Koepka bt Russell Henley 1 up
Group 13: Rickie Fowler bt Harris English 1 up
Group 13: Shane Lowry (Irl) bt Graeme McDowell (N Irl) 1 up
Group 14: Hunter Mahan (USA) bt Stephen Gallacher 7 and 6
Group 14: Ben Martin bt Matt Kuchar 1 up
Group 15: Patrick Reed bt Andy Sullivan (Eng) 2 and 1
Group 15: Danny Willett (Eng) bt Ryan Moore 3 and 2
Group 16: Hideki Matsuyama (Jpn) bt Alexander Levy (Fra) 5 and 4
Group 16: Joost Luiten (Ned) bt Kevin Na (USA) 19 Holes