Hunter Mahan fired an 8-under 64 on Friday to move two strokes clear of the field after two rounds of the Canadian Open.
Mahan, who has been in the final group at the last two majors, ended 36 holes at 13-under-par 131.
John Merrick fired a 10-under 62 to soar into second place at minus-11. Bubba Watson is alone in third at 9-under 135 after a second-round 67.
Aaron Baddeley and Patrick Reed have both posted back-to-back 68s and they share fourth at 8-under 136. Tommy Gainey carded a 64 to climb into a share sixth at minus-7. He was joined there by James Hahn (68) and Chris Kirk (69).
First-round leader Brendan Steele struggled to a 3-over 75 and tumbled into a share of 26th at 4-under 140 at Glen Abbey Golf Club.
MORE TO FOLLOW.