All four top seeds advanced on Thursday. Two-time defending champion Tiger Woods easily disposed of Hall of Famer Nick Price, 4 and 3, in the Gary Player bracket.
Woods captured the first hole with a par, then never looked back. He won the fourth, sixth and eighth holes to basically put the match out of reach. Woods closed out the contest on the 15th hole.
'Nick gave me the first hole and I was able to stick it out. It was a nice little quick start,' said Woods, who defeated Davis Love III in last year's final. 'Today was most important to get off to a quick start in match play. I was able to do that.'
Phil Mickelson, who won his last two starts on tour, lost two holes late, but still bested Loren Roberts, 3 and 1, in the Sam Snead bracket.
Vijay Singh, No. 1 in the Bobby Jones bracket, dispatched Shingo Katayama, 4 and 3. Retief Goosen, tops in the Hogan bracket, had the toughest time of the top seeds in the first round. He went 18 holes before defeating last year's semifinalist Stephen Leaney, 1 up.
Triplett's win was the biggest upset in Thursday's first round, where tees were up and play was contested under lift, clean and place. Heavy rain in southern California over the last few weeks left La Costa unplayable on Wednesday, when the first round was scheduled to be contested. Both the second and third rounds will take place on Friday in an effort to get the tournament finished on time.
Triplett, the 15th seed, found himself 1 down after seven holes, but won the next two with birdies to go 1 up. Weir knotted the match, but Triplett took the 12th and 14th with pars to move 2 up.
Weir was 2 down with two to play and made things interesting. He won the 17th then sank a clutch 18-footer for birdie at the par-5 closing hole to put pressure on Triplett. Unfortunately for Weir, Triplett ran in a 5-footer to hang on for the victory.
'I drug Mike right down in the mud with me today and we rolled around for a while,' said Triplett. 'Mike didn't play well at all, so I caught him on a bad day. I almost didn't play well enough to take advantage of it.'
Triplett will now face Craig Parry in the second round as Parry squeaked out a 1 up win over Tim Clark.
The other big upset of Thursday's first round also occurred in the bottom half of the Hogan bracket. Darren Clarke, the 2000 champion and third seed, lost 1 down to the only other Northern Irelander in the field, Graeme McDowell.
McDowell will take on Robert Allenby on Friday. Allenby, the 11th seed, trounced reigning British Open winner Todd Hamilton, 6 and 5.
Goosen will face ninth seed Fred Couples on Friday after Couples beat Peter Lonard, 1 up. Chad Campbell, the fifth seed, defeated Fredrik Jacobson, 2 up, and will take on Miguel Angel Jimenez, the fourth seed who dispatched Rod Pampling, 3 and 2.
Woods' bracket featured the only two matches to go extra holes on Thursday. Nick O'Hern, seeded eighth, drained a 20-footer on the 19th hole to defeat Charles Howell III, 1 up.
Stuart Appleby, the third seed, also needed one more hole to beat Joakim Haeggman, 1 up. Appleby, who won the season-opening Mercedes Championships, is scheduled to meet Ian Poulter, a 3 and 1 winner over sixth-seeded Jim Furyk.
Luke Donald won, 4 and 3, against Zach Johnson and the fifth seed will take on fourth seed Kenny Perry, who stopped Thomas Levet, 3 and 2. Padraig Harrington, No. 2, birdied 18 to beat Jeff Maggert, 1 up. Harrington will battle Rory Sabbatini in the second round of the Player bracket as the South African pummeled seventh seed, Thomas Bjorn.
In the Snead bracket, Mickelson will face eighth-seeded Angel Cabrera in the second round. Cabrera was never in danger as he posted a 4 and 2 win over Paul Casey.
Adam Scott, who won last week's rain-shortened Nissan Open, survived a scare from No. 14 seed Trevor Immelman on Thursday. Immelman chipped in for birdie to win the 17th and cut the margin to 1-down, but Scott won 18 to post a 2 up victory. Scott will meet 11th-seeded David Howell in the second round after Howell handled Shigeki Maruyama, 6 and 5.
'Every match is tough. That's just how it is,' said Scott. 'It's the top 65 players in the world, so every match is going to be tough. Whether I'm playing Tiger or David Howell, I am expecting it to be some good golf and maybe have to shoot a good number to win.'
David Toms, the fourth seed in the Snead bracket and second-place finisher to Woods in 2003, notched a 1 up victory over Richard Green on Thursday. Toms will meet Mark Hensby on Friday as Hensby equaled the tournament record for shortest match with a 7 and 6 whipping over Stephen Ames on Thursday.
Sergio Garcia, the No. 2 seed, defeated Alex Cejka, 4 and 2, and is set to play Jerry Kelly on Friday. Kelly advanced with a 1 up win over Scott Verplank.
Singh will get Jay Haas in round two. Haas moved on with a 4 and 2 thumping of Jonathan Kaye. John Daly, the 12th seed in the Jones bracket, won the 15th and 16th holes, then held on to beat Justin Leonard, 1 up.
'Today was a very tough match,' said Daly. 'Justin has been playing great. He won Bob Hope this year. I just hung in there. He missed a few putts for me, too.'
Daly will take on Chris DiMarco, the fourth seed, on Friday after DiMarco knocked off Tim Herron, 1 up.
American Ryder Cup captain Tom Lehman looked impressive on Thursday as he upset seven seed, K.J. Choi, 4 and 2. Lehman will now face a player who will likely be on Lehman's team next year, Stewart Cink. Cink beat Fred Funk, 2 up.
Love dispatched Chris Riley, 1 up in the first match of the first round. Love will now go up against Lee Westwood in the second round after Westwood dismissed Steve Flesch, 4 and 3.