Louis Oosthuizen fired a flawless seven-under-par 64 to take a one-shot lead after the opening round of the WGC-Mexico Championship at Club de Golf Chapultepec.
On a rather surprising leaderboard, his closest pursuers include two players making their first ever start in a WGC event, England's Chris Paisley and Indian Shubhankar Sharma.
The duo, who have both won on the European Tour this year, are on six-under alongside last year's Tour Championship winner Xander Schauffele while it's a shot further back to Rafa Cabrera Bello and Kiradech Aphibarnrat.
As for the big guns, Jon Rahm is solo seventh after a four-under 67, world number one and defending champion Dustin Johnson is at two-under while Jordan Spieth is tied 23rd after a one-under 70.
Former Open champion Oosthuizen set the tone for his impressive opening lap with a pair of opening birdies and picked up another shot at the fifth. He continued his push with birdies at 10 and 12 before hitting his approach to the par-five 15th to inside five feet and holing the putt for eagle.
"I'm very confident with my driver at the moment. Had a nice little cut going with it, just aiming it a little left and just swing away," said the South African.
"I've been swinging it pretty good the last three, four weeks. Felt I played really well last week (tied 24th in Honda Classic), just got caught in the Bear Trap (tough closing holes) a little bit.
"Yeah, I'm hitting it well and just need to do the same tomorrow. You know, the greens can be a little bumpy at the end of the day, but I hit a few really close."
The ball is carrying further in the altitude this week, which is an added complication, but Oosthuizen said he and his caddie were comfortable with it.
"Whenever we played up in Johannesburg or Sun City, it's altitude and you know the ball's going further. Here, it's actually going a little further. But I've played in it before and it helps knowing what the ball does," he added.
Oosthuizen is 2500/1 to win the WGC-Mexico Championship, with Rahm 2500/1, Johnson 800/1, Schauffele 2000/1 and Rickie Fowler (-3) 2500/1.
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