MEXICO CITY — Abraham Ancer knows all about altitude, and not just the thin air at Chapultepec Golf Club where he returns to the Mexico Championship under entirely different circumstances.

He played in this World Golf Championship the last two years because of a provision in the criteria that a spot be reserved for the highest-ranked Mexican player.

Now his game and his confidence are soaring.

Ancer earned a place in the elite field this year from having reached the FedEx Cup finale, rising to No. 29 in the world and feeling as though better days are still to come.

And it all started a year ago on the first tee at Chapultepec when he was paired with Tiger Woods.

“I'm always nervous in this event. I always just want to perform so well in this tournament,” he said Wednesday. “You add Tiger to the equation, it was really a big thing for me. But it helped me a lot. At the moment, I didn't realize how much it was going to help me.”

He found calm in situations that once left him on edge. That carried him to a runner-up finish in the FedEx Cup playoffs opener, to a Presidents Cup debut in which he led the International team in points and gave Woods all he could handle in a singles match, and to his closing 63 in the California desert last month for another runner-up finish.

The timing couldn't have been better for Mexico.

The PGA Tour decided last summer to update the criteria for the Mexico Championship. If a Mexican player earned his way into the field, another Mexican could play provided he was among the top 300 in the world.

That turned out to be Carlos Ortiz, who could only watch from outside the ropes the last few years. Both were on the developmental Korn Ferry Tour the first year of the Mexico Championship.

“Today golf in Mexico is stronger than ever,” said Benjamin Salinas, head of Television Azteca and part of the Grupo Salinas that sponsors the event. “We have two Mexican players among the best in the world competing together for the first time in this type of tournament. All Mexico is supporting you this week.”

More pressure for Ancer. He's getting used to this.

Jon Rahm can appreciate what he's going through, having returned home to Spain for the Spanish Open and winning it each of the last two years. It's a little different for Rahm because he already is a nine-time winner and has another chance this week to reach No. 1 in the world.

“It's a very unique feeling when you feel the better part of a country or the following that week supporting just one or two players,” Rahm said. "They're proud to have you there perform and you should be proud to be there performing for them. A lot of times when you have that behind you, it's like an extra motivator that helps you do better.

“It's also at the same time hard to control the willingness or the want to do good for yourself and for them,” he said. “At the end of the day, you're playing for yourself, and by playing good for yourself you're going to entertain them.”

Ancer won't have to worry about additional attention with Woods, who chose not to play this year. Also missing from the top 10 are Brooks Koepka and Patrick Cantlay, who faces elective surgery for a deviated septum.

Ancer plays with defending champion Dustin Johnson and Francesco Molinari. Ortiz will be playing with Rahm and Adam Scott, the winner last week at Riviera.

Ortiz is among eight players in a World Golf Championship for the first time. This is a different test, playing at roughly 7,500 feet altitude, meaning players have been spending more time than usual on the range trying to figure out how far the golf ball is flying.

Johnson won in 2017 and 2019 and is trying to end a full year without winning, his longest drought in more than four years. Rory McIlroy has a chance to join Johnson as the only players to win all four WGCs.

There's a lot at stake this week, including the No. 1 ranking between McIlroy and Rahm.

Ancer will be feeling his own pressure.

He already has come a long way from Odessa Junior College in Texas, performing well enough to get the attention of Oklahoma, and then plodding along through the developmental tours to reach No. 29 in the world.

“It's been that way my whole life,” Ancer said. “Always getting a little better.”

He got a lot better in the last year, and with that comes higher expectations and slightly more pressure before a home crowd in Mexico.

“I still feel nervous, but I know how to control it in a way,” Ancer said. “But yeah, I do feel a little more pressure because I really want to play good here.”