MEXICO CITY -- Rory McIlroy flirted with a hole-in-one on the same par 4 where Tiger Woods hit out of bounds with his first shot in Mexico.

That's about how their days went Thursday in the Mexico Championship.

McIlroy, already off to a solid start on the back nine, hit a 2-iron on the 305-yard opening hole at Chapultepec Golf Club that landed on the front of the green and was rolling just left of the pin when it settled 6 feet away, leading to an eagle that carried him to an 8-under 63 and a one-shot lead over Dustin Johnson.

Woods got the raucous Mexican introduction for his opening tee shot, a 5-wood that also landed on the green -- the wrong green. The ball bounced hard off a temporary green to the left and beyond the out-of-bounds stake into the bushes.

And then he nearly did it again and ultimately had to get up and down from 60 feet away in a bunker to escape with double bogey. After a burst of birdies, he struggled to make much the rest of the way and opened with a 71.

McIlroy's 2-iron was the signature shot in an exquisite start to this World Golf Championship. He was 6 under through an eight-hole stretch in the middle of the round, and a 20-foot birdie on No. 8 toward the end of his round is what gave him the lead over Johnson, who played in the group behind.

It was his second straight week with a 63.

"I wouldn't say it was easy," McIlroy said. "I hit a lot of good golf shots, but I left myself a lot of tap-ins for birdies. As 63s go, I shot 63 at Riviera last week, but this felt probably a little more stress-free."

He described his 2-iron as close to perfect, just how he envisioned it, a little cut to take off some distance in the thin air of Mexico City.

The only blemish on his round came at the par-5 sixth, when he pulled his tee shot into the trees and looked as though he would have to punch out back to the fairway. Standing over the ball, McIlroy was looking up. He saw a gap between two trees with tiny limbs, so even if he clipped one, his 8-iron should have been enough to give him a reasonable shot at the green.

There was one limb that concerned him, which McIlroy described as "something a dog would pick up."

Rory McIlroy plays his shot from the seventh tee during the first round of the Mexico Championship golf tournament at Club de Golf Chapultepec in Mexico City on Thursday. Orlando Ramirez-USA TODAY Sports

"The one branch it could not hit, it hit," he said. "It all levels out at the end of the day. I'm just in a good frame of mind, managing my game well, putting went good. And if you putt well, it takes pressure off the rest of your game. And that's where it's at."

Johnson won the Mexico Championship two years ago, part of three straight victories during the best stretch of golf he ever played. Johnson said he struggled with his swing at Pebble Beach and Riviera and worked all week on the range in Mexico.

"It's starting to feel the way it did two years ago," he said.

Much like McIlroy, there wasn't a lot of stress in his game. Johnson missed only three of the tree-lined fairways and was rarely out of position except on No. 12, where he lost his drive well to the right. He had no shot to the green, so he tried to put it in the bunker. It went in and out of the bunker, onto the fringe, and he holed the putt from 20 feet for his third straight birdie to start the round.

He also had back-to-back eagle putts, driving the first green to 20 feet and hitting driver on the 383-yard second hole over the trees and onto the green -- as Bubba Watson was putting -- to 18 feet. He made birdie on both.

"I feel like I've got this altitude thing figured out," he said.

Justin Thomas, who lost in a playoff last year to Phil Mickelson, chipped in from 50 feet behind the green on No. 15 for eagle and was at 66. He was tied with Matt Kuchar, who already won in Mexico once this season at the Mayakoba Classic.

Jordan Spieth, with his father filling in because caddie Michael Greller's father died, opened with a 75.

Mickelson, two weeks removed from his victory at Pebble Beach, bogeyed three of his first four holes on the back, shot 40 on the front and opened with a 79.

Information from The Associated Press was used in this report.