World No. 1 Rory McIlroy fired a 6-under-par 65 in tricky winds on Thursday to build a two-shot lead after the first round of the WGC-Mexico Championship in Mexico City.
FedEx Cup leader Justin Thomas and Bubba Watson are tied for second at 4 under, followed by Bryson DeChambeau, Billy Horschel,Canada's Corey Conners and South Africa's Louis Oosthuizen another shot off the pace.
The runner-up at Club de Golf Chapultepec last year, McIlroy arrived in Mexico City with four top-5 finishes under his belt to begin 2020.
Starting on the back nine Thursday, McIlroy continued to eat up the par-5s -- sinking an eagle on the 11th hole and a birdie on the 15th to make his turn in 3 under. He added four more birdies against a lone bogey on his back nine.
"I like this place, I like the golf course," McIlroy told the Golf Channel of Chapultepec, where the lowest elevation is 7,603 feet above sea level. "I've always played pretty well at altitude, for whatever reason that is.
"I got beat last year (by Dustin Johnson), I didn't lose. I played pretty well, and hopefully this year I can do one better."
McIlroy also took advantage of his switch back to the 34-inch putter that he used last year after struggling with a 35-inch putter at the Genesis Invitational last week. He needed only 26 putts while hitting 12 of 18 greens in regulation Thursday.
"It worked pretty well last year, so I'm gonna keep it in the bag," McIlroy said. "It worked really well today. Happy to have the old faithful back in the bag, and it worked pretty well today."
McIlroy, who also won the season-opening WGC event in Shanghai in November, has been inside the top 10 in 13 of his last 14 rounds on the PGA Tour, per the Golf Channel. He also shot a 63 to lead after the first round in Mexico last year.
Adam Scott, coming off wins in his past two starts, struggled to a 3-over 74. The Australian made the turn at 1 under, but bogeyed two of his next three holes before a double bogey on the par-4 14th.
Johnson had four bogeys and a double in posting a 5-over 76. It was his first over-par round in 13 career rounds at Chapultepec, where he had 11 consecutive rounds in the 60s entering the week.
Thomas, who holds the course record with a 62, posted another strong round with Thursday's 67 that featured five birdies against a lone bogey. He acknowledged that the winds combined with altitude made for a challenging test -- McIlroy hit a 4 iron 285 yards in setting up his eagle and Thomas said he hit a 6 iron from 240 yards over water.
"It's a different course," Thomas told the Golf Channel. "I felt like today was tough, I've never played this place with this kind of wind. It just doesn't get this windy here that often.
"You can go so low but, man, if you're not playing well you can shoot over par in a heartbeat. So it's pretty tough to manage your score, but I feel like we have a pretty good idea how far the ball goes, and that helps."
NOTES: This is a no-cut event. ... Mexico's first representative in the Presidents Cup, Abraham Ancer overcame two bogeys in his first four holes to post a 1-under 70. ... McIlroy is attempting to join Johnson as the only players to win all four WGC titles in a career, dubbed the "WGC Slam." ... Johnson is seeking to become the first player to successfully defend at the event since Tiger Woods from 2005-07. ... The field includes 42 of the top 50 players in the world rankings.
--Field Level Media