Tournament favourite Jon Rahm is joint-leader of the Mexico Open, posting a seven-under 64 in Thursday's first round.

Rahm, ranked number two in the world, went bogey-free in his round, with six birdies and an eagle on the par-four seventh hole.

He is in a five-way tie atop the leaderboard with Americans Jonathan Byrd, Trey Mullinax, Bryson Nimmer and Brendon Todd.

Speaking with the media after stepping off the 18th green, Rahm highlighted his success with the driver, finding the fairway with 12 of his 13 long-balls.

"When I feel at my best, I’m pretty much comfortable hitting driver anywhere," he said

"It was one of those rounds where it felt like everything clicked together. Short game was good, had a chip-in, putting was good and tee to green was fantastic… probably as solid a round as I played all year."

While he enjoyed his round, Rahm spoke about how the conditions changed towards the end of his day, and how it could play far tougher the rest of the weekend.

"Although I went into a little dry spell, I didn’t care about it so much because it is not the easiest golf course," he said.

"The one thing to keep in mind for people watching the scores – there’s a big difference between morning and afternoon (conditions). We had no wind for 13, 14 holes – it’s very, very scoreable. 

"Once the wind starts going 20, 30 miles an hour, this golf course starts showing some teeth."

England's Aaron Rai is one shot further back, along with Sahith Theegala, Aaron Wise and Scott Brown, trailed by a large group at five under, highlighted by Colombia's Sebastian Munoz.

Cameron Champ and Patrick Reed are one more shot back at four under, while Alvaro Ortiz is the highest placed of the Mexican contingent at three under, ahead of Armando Favela and Carlos Ortiz, who both shot 70.

In-form Davis Riley finished at two under, while Tony Finau and Cameron Tringale had disappointing days at even par, with the latter bogeying both the 17th and 18th to finish his round.