Montreal - US Open champion Dustin Johnson shook off a double-bogey to maintain a share of the lead alongside Luke List on Friday after two rounds of the PGA Tour Canadian Open.
Johnson, who started the day tied with List for the lead, fell back early as he dropped four shots in his first four holes at Glen Abbey near Toronto.
With warm sunshine drying out the course, Johnson teed off on 10 and promptly bogeyed 11. He dropped two shots at 12 and bogeyed 13 before pulling back a couple of shots at 16 and 18.
With his confidence high in the wake of his first major triumph at the US Open, Johnson said he didn't panic.
"I didn't feel like I hit bad shots," he said. "Just got in a couple of awkward spots. I knew I was playing well."
With four more birdies coming in and one bogey at his penultimate hole Johnson signed for a one-under 71 that left him tied with List on seven-under 137.
While he thought his game was on, Johnson acknowledged that the windy weather and firm course made for a challenging day.
List's 71 had its rocky moments, but he picked up two of his four birdies at 16 and 18 -- after making three bogeys in four holes on the back nine.
Canadian amateur Jared du Toit, Spain's Jon Rahm and American Kelly Kraft were a stroke back on 138. All three also carded 71s.
Du Toit was tied for the lead through nine holes, but surrendered a triple-bogey eight on the par-five second hole and bogeyed the fifth. He bounced back with three straight birdies to stay in the hunt.
England-born Canadian Pat Fletcher is the last Canadian to win the title, back in 1954 in Vancouver.
World number one and defending champion Jason Day of Australia was one-over through 36 holes after a second-round 76.
"The day was pretty tough in itself and then I really didn't have anything going well," Day said. "Off the tee was terrible. Hitting the greens were terrible. Chipping was terrible and putting was terrible. So put all that together, you shoot four-over."
Day said he hadn't adjusted well to the firm greens this week.
"When your speed is off, it's really hard to hit your line and trust it," he said.
Having made the cut, he said, he would just try to enjoy the weekend as he looks ahead to next week's PGA Championship, the fourth major of the year that has been moved up in the calendar to allow for golf's return to the Olympics in August.
"I'm just going to go out there and try and enjoy myself. Try and work on things that need to be worked on for the PGA," Day said.
"I've just got to play really, really good golf over the weekend to even have a sniff at catching them. I've just got to try and enjoy myself first more so than what I have the last two days."
137 - Dustin Johnson 66-71, Luke List 66-71
138 - Jon Rahm (ESP) 67-71, Kelly Kraft 67-71, a-Jared du Toit (CAN) 67-71
139 - Ricky Barnes 71-68, Ben Crane 69-70, Tyler Aldridge 69-, Brendon de Jonge (RSA) 68-71
140 - Chad Campbell 73-67, Alex Cejka (GER) 71-69, Kevin Kisner 73-67, Chez Reavie 69-71, Matt Kuchar 69-71, Noh Seung-Yul (KOR) 70-70
141 - Jim Furyk 70-71, Vijay Singh (FIJ) 72-69, K.J. Choi (KOR) 71-70, Brandt Snedeker 68-73, Cameron Tringale 68-73