Mexico City - Dustin Johnson fired his second straight bogey-free round on Friday, a four-under par 67 that gave him a two-stroke lead over Rory McIlroy and Matt Kuchar at the WGC-Mexico Championship.
Johnson's methodical approach at Club de Golf Chapultepec paid dividends as he overhauled first-round leader McIlroy on a day when 14-time major champion Tiger Woods moved into the top 10 with a five-under 66.
"I've just done a really good job with controlling my distance with my irons and giving myself a lot of looks at birdies," said Johnson, who had never before in his US PGA Tour career opened a tournament with two bogey-free rounds.
The 2017 WGC-Mexico champion said he enjoyed the challenge of adjusting to the altitude.
"It makes you focus, you've got to think and you're doing a lot of calculations with the numbers, trying to figure out how far the ball is going to actually go," he said.
McIlroy, who opened Thursday with an eight-under par 63, picked up where he left off with three birdies in his first four holes.
But he found the water for a bogey at the sixth and then made a double-bogey at the par-four ninth, where he was 15 feet from the fringe with his second shot but needed four putts from there.
He signed for a one-under 71 for nine-under 133. He was joined by Kuchar, who opened with four straight birdies in a four-under 67.
Spain's Sergio Garcia and England's Tommy Fleetwood were tied for fourth on 135, Garcia posting a 66 and Fleetwood a 65 that started with back-to-back eagles at the first and second - both par-fours.
Fleetwood tied for low round of the day with Phil Mickelson, who had opened his title defence with a horrendous 79, only to bounce back with a bogey-free 65.
Woods climbed the leaderboard with a five-under 66 that featured six birdies and an unlikely par at his finishing hole, the par-four ninth.
In a fairway bunker off the tee, Woods produced a vintage recovery shot, cutting a nine-iron around a tree, the ball spinning back some 20 feet toward the hole.
It left him an 11-foot birdie putt that lipped out.
"The ball was sitting down just enough where I didn't think I could clear the tree," said Woods, who first went for his eight-iron but decided it would come out too hot.
"I went back to the nine-iron, I realised 'I've really got to slice this thing,'" he said.
"I opened up and gave it as much of a cut motion as I could and it worked out."
Woods had made a scrambling start to his round, rolling in a nine-footer for his first birdie at the 12th. He birdied 14 and got up and down for birdie from a greenside bunker at 15.
He gave a shot back at 17, but drained a 13-footer at 18 to make the turn three-under. He rolled in a 22-footer for birdie at the third and picked up another shot at the fifth to stand tied for eighth - six shots off the lead - heading into the weekend.
Leading second-round scores on Friday in the World Golf Championships-Mexico Championship (USA unless noted, par-71):
131 - Dustin Johnson 64-67
133 - Rory McIlroy (NIR) 63-70, Matt Kuchar 66-67
135 - Sergio Garcia (ESP) 69-66, Tommy Fleetwood (ENG) 70-65
136 - Cameron Smith (AUS) 69-67, Ian Poulter (ENG) 68-68
- Kiradech Aphibarnrat (THA) 68-69, Richard Sterne (RSA) 69-68, Charles
Howell 69-68, Tiger Woods 71-66, Tyrrell Hatton (ENG) 67-70
138 - Louis Oosthuizen (RSA) 72-66, Francesco Molinari (ITA) 71-67, Joost Luiten (NED) 71-67
139 - Jake McLeod (AUS) 70-69, Patrick Cantlay 72-67, David Lipsky 68-71, Justin Thomas 66-73
140 - Kevin Kisner 73-67, Patrick Reed 72-68, Erik van Rooyen (RSA) 72-68, Shugo Imahira (JPN) 73-67, Danny Willett (ENG) 71-69
141 - George Coetzee (RSA) 67-74, Aaron Wise 73-68, Li Haotong (CHN) 69-72