Rory McIlroy made a convincing start with an early victory on the opening day of the WGC-Dell Technologies Match Play.
McIlroy, who won the title in 2015 but has failed to get out of the group stage in his last two appearances, claimed a 5&4 victory over Luke List in his first match of the day.
The Northern Irish golfer took the lead on the second hole and never relinquished it, sealing victory with birdies on the 13th and 14th.
There was no such joy for Shane Lowry who lost 4&2 to Sergio Garcia, despite attempting a late fightback.
Lowry got off to a poor start and lost the first hole to Garcia's birdie and at the turn was four holes down, before a bogey on the 10th left him struggling.
However birdies on the 12th and 13th holes gave the Irishman hope of an unlikely comeback before he eventually conceded on the 16th to wrap up the match.
Elsewhere, Ryder Cup partners Tommy Fleetwood and Francesco Molinari renewed their love affair with match-play golf.
Fleetwood was two down after six holes to Korea's Byeong Hun An before rallying to win 3&2, while Molinari beat Satoshi Kodaira 5&4.
Fleetwood and Molinari became the first European pair to win all four of their matches together in September's Ryder Cup victory over the United States at Le Golf National, with Open champion Molinari finishing with a perfect 5-0 record.
"I've lost the first day and then won the group and I've won the first day and finished last in the group," Fleetwood told Sky Sports. "But it's great to have a good first day because once you lose you are behind the game and have to catch up.
"I had a good break around eight and nine. He had a three-putt on eight and missed a chance on nine and it kind of flipped the game around."
Scotland's Russell Knox faces a daunting task to reach the semi-finals and qualify for the Masters after suffering a 3&1 defeat to Bryson DeChambeau, but Paul Casey continued his superb recent form with victory over Mexico's Abraham Ancer.
Casey, who successfully defended his title in the Valspar Championship last week, was one down after five holes but recovered to win 5&3, while Ryder Cup team-mate Alex Noren suffered a heavy defeat to China's Li Haotong.
Tiger Woods, making his first appearance in the event since 2013, defeated Aaron Wise 3&1 in a scrappy contest and admitted: "Neither one of us really played that great today.
"It was a pretty emotional match because we were up and down, up and down, there weren't a lot of holes halved and I was just kind of hanging in there. It was one of those matches where we weren't playing our best and on a golf course like this it kind of exposed us a little bit."
The 64 players are split into 16 groups of four, with only the group winners advancing to the knockout stages at the weekend.
