MEXICO CITY - Bryson DeChambeau kept making so many birdies in the Mexico Championship that when he rolled in his ninth one from 45 feet, all he could do was throw his hands in the air in pure wonder.
He wasn't alone Friday in making birdies, although Rory McIlroy would like to have joined the party.
DeChambeau made seven birdies in an eight-hole stretch at Chapultepec Golf Club for an 8-under 63, giving him a one-shot lead over Erik van Rooyen of South Africa and Patrick Reed at the halfway point of this World Golf Championship. DeChambeau was at 11-under 131.
Van Rooyen, who played college golf at Minnesota, celebrated his 30th birthday by making nine birdies to tie the course record with a 62. Reed made five birdies on the back nine for a 63
Justin Thomas ran off four straight birdies to end the back nine, and then holed a 35-foot eagle putt to build a three-shot lead through 10 holes. That was gone in a matter of four holes as player after player kept rolling in putts on a day with much less wind and far better scoring. The average score 70.28, more than two shots better than Thursday.
Hideki Matusyama was 9 under for his round through 15 holes and had a 20-footer birdie attempt from the fringe on the par-3 seventh. He missed that 3 feet to the left, then missed the next one. He bogeyed the next hole, too, and had to settle for a 64. That left him at 9-under 133, along with Thomas, who had to settle for a 66.
McIlroy wasn't so fortunate. Staked to a two-shot lead at the start of the day, he opened with eight straight pars, didn't make a birdie until his 12th hole and fell six shots behind at one point. Two birdies at the end gave him a 69, and the world's No. 1 player was only three shots behind.
"I made eight pars in a row, and then it's like, 'OK, you're either going to make a birdie or a bogey. What's going to come first?' And I ended up making bogey," McIlroy said. "There's a long way to go."
DeChambeau can use all the science he wants with calculations for altitude and air density. The difference for him on this day wasn't that difficult to figure out.
"I just made a lot of putts today," he said.
His big run began on the 18th hole with a 15-foot birdie putt. He got up-and-down from short of the green on the reachable par-4 first hole, made a 15-footer on the net hole, added a few birdies inside 6 feet, and then made a 25-foot birdie. That apparently wasn't enough.
His tee shot on the 223-yard seventh hole with a green fronted by water wenttoward the back of the putting surface, leaving DeChambeau a downhill putt that is tough to lag. His putt was perfect pace, and a perfect line, as it turned out.
"I just threw my hands up in the air. I mean, come on. Who thinks I'm going to make this one?" DeChambeau said. "Matt (Fitzpatrick) just looked at me and he was like, 'What are you doing? Go get a lottery ticket or something.'"
Reed seems to play his best with a chip on his shoulder, and his 63 comes after a week in which Brooks Koepka and ex-CBS broadcaster Peter Kostis brought up his rules violation in the Bahamas, stirring more bad memories.
"I'm not going to lie, just the whole thing on the outside distracts us from our ultimate goal, and that's to go out and play great golf and continue to try to improve every day on and off the golf course," Reed said. "As long as you're doing that, then you're living the right way. So at the end of the day, you can't please everybody, and I feel like I'm doing everything I need to be doing to continue to strive in the game of golf, hopefully on and off the golf course."
Most intriguing of the lot is van Rooyen, who finished the year among the top 50 to earn his first trip to the Masters.
Now it's about building a schedule on the road to Augusta. He has a sponsor exemption to the Honda Classic - van Rooyen moved to the area last summer - and needs to be in the top 50 each of the next two weeks to get into the Arnold Palmer Invitational and The Players Championship. He currently is at No. 52.
"I think at a tournament like this and a field like this, if you can play well, you can play well anywhere," van Rooyen said. "So if I continue the way I'm going, it'll be a big confidence booster."
Defending champion Dustin Johnson continued to struggle. A two-time winner in Mexico, Johnson has made only three birdies in two days. He shot 71 on Friday and was 16 shots behind.
Mexico Championship Scores
Friday
Second Round
Bryson DeChambeau 68-63-131
Erik van Rooyen 70-62-132
Patrick Reed 69-63-132
Hideki Matsuyama 69-64-133
Justin Thomas 67-66-133
Rory McIlroy 65-69-134
Sebastin Muoz 71-66-137
Tyrrell Hatton 69-68-137
Paul Casey 69-68-137
Corey Conners 68-70-138
Lee Westwood 69-70-139
Kevin Na 71-68-139
Matthias Schwab 71-68-139
Billy Horschel 68-71-139
Bubba Watson 67-72-139
Louis Oosthuizen 68-71-139
Tommy Fleetwood 70-69-139
Gary Woodland 70-69-139
Zach Murray 71-69-140
Ryan Fox 72-68-140
Abraham Ancer 70-70-140
Danny Willett 73-68-141
Jon Rahm 72-69-141
Zander Lombard 73-68-141
Shane Lowry 72-69-141
Lanto Griffin 72-69-141
Sungjae Im 69-72-141
Collin Morikawa 72-70-142
Justin Harding 71-71-142
Matthew Fitzpatrick 72-70-142
Adam Scott 74-68-142
Rafa Cabrera Bello 71-71-142
Kevin Kisner 73-69-142
Matt Kuchar 75-67-142
Branden Grace 71-71-142
Benjamin Hebert 73-70-143
Scottie Scheffler 73-70-143
Carlos Ortiz 75-68-143
Jason Kokrak 73-70-143
Shaun Norris 75-68-143
Brendon Todd 72-71-143
Robert MacIntyre 76-68-144
Marc Leishman 74-70-144
Shugo Imahira 74-70-144
Lucas Glover 71-73-144
Byeong Hun An 75-69-144
Xander Schauffele 72-72-144
C. Bezuidenhout 72-72-144
Chez Reavie 71-73-144
Lucas Herbert 75-70-145
Webb Simpson 72-73-145
Brandt Snedeker 76-69-145
Pablo Larrazabal 71-74-145
Kurt Kitayama 76-70-146
Bernd Wiesberger 70-76-146
Sergio Garcia 74-72-146
J. Janewattananond 73-73-146
Cameron Smith 73-73-146
Francesco Molinari 72-74-146
Jordan Spieth 74-73-147
Scott Hend 72-75-147
Dustin Johnson 76-71-147
Charles Howell III 75-74-149
M. Lorenzo-Vera 76-73-149
Marcus Kinhult 75-74-149
Graeme McDowell 76-74-150
Victor Perez 81-70-151
Matt Wallace 74-77-151
Jorge Campillo 77-74-151
Sung Kang 76-76-152
Ryo Ishikawa 80-72-152
Tae Hee Lee 80-73-153