Tim Clark nearly set a new course record at Hamilton but had to settle for 62 to jump into contention at the RBC Canadian Open.
Clark jumped from even at the start of the day to 8 under and three shots behind leaders Scott Piercy (67) and William McGirt (66).
Robert Garrigus shot 66 to trail by a shot and sit alone in third place. Bo Van Pelt is another shot back in fourth.
Joining Clark in a tie for fifth are Josh Teater and Vijay Singh.
Open champion Ernie Els missed the cut by two shots, finishing at 2 over par.