Brendan Steele topped the Canadian Open leaderboard Thursday at 7-under 65, birdieing five of the first seven holes on his back nine at Glen Abbey.
The 30-year-old Steele, winless on the PGA Tour, had eight birdies and a bogey, dropping a shot on his final hole - the par-4 ninth.
Matt Kuchar, a two-time winner this year, was a stroke back along with Scott Gardiner and Scott Brown. Kuchar eagled the par-5 18th hole, his ninth hole of the day.
Hunter Mahan and David Lingmerth shot 67, and Chez Reavie, the 2008 winner at Glen Abbey, was another stroke back in a group that included Bubba Watson and Trevor Immelman.