Johnson has won five World Championships golf WGC-Mexico championship second round – 11 D Johnson (USA); -9 R McIlroy (NI), M Kuchar (USA); -7 S Garcia (Spa), T Fleetwood (Eng); -6 C Smith (Aus), I Poulter (Eng) Other selected: -5 T Woods (USA), T Hatton (Eng); -2 D Willett (Eng); +1 M Fitzpatrick (P), P Casey (Eng)
Dustin Johnson shot a four-under-par 67 to lead by two wins in the half-stage of the WGC-Mexico championship.
The 34-year old American, twice winner of the event, is 11 below average and has to drop a week this week.
Rory McIlroy was four shots at one stage but shares second night after a four-man double bogeyman in a 70.
Englishman Tommy Fleetwood started his round with successive eagles and is four of the lead after a 65, while Tiger Woods is five after a 66.
McIlroy opened with successive birdies and also took a shot at the fourth, but the sixth hole cost him a chance for the second day in a row – and four putts from the edge of the ninth green meant that he gave up the lead.
"These greens, with some traffic on them, get a bit crunchy and it's hard to trust your lines, but I'm still in a good position," said the Northern Irishman, who is right with American Matt Kuchar.
Ian Poulter from England opened with a double bogeyman on the 10th but seven birdies helped him to a second consecutive 68 and a share of the sixth.
Defending champion Phil Mickelson, who opened with a 79 that left him only one place on the leaderboard, birdied the first three holes of his second round and returned a 65 to move two.
World number nine Rickie Fowler had a remarkable round, which began on the 10th with a shaft out of reach of his second shot. He then dropped from shoulder height, in violation of new laws filed at the beginning of the year, and received a penalty, resulting in a triple bogey.
The 30-year-old had two double bogeys but also made six birdies in a 73 for a two-over halfway total.