American pair Scott Piercy and William McGirt hold a share of the lead at the midway point of the Canadian Open, but Australians Gavin Coles and Stuart Appleby are within striking distance.
McGirt shot a four-under 66 to sit 11-under overall, while Piercy went three under for his second round at the Hamilton Golf and Country Club on Friday.
The day's honours, however, belonged to South Africa's Tim Clark, who equalled the course record in Ontario, with an eight-under 62 to be tied for fifth - after Piercy set the record in the opening round.
Six birdies and an eagle on the par-four second hole saw Clark to within three strokes of the leaders after an indifferent opening round of even par.
Level with Clark on eight-under overall is Fijian Vijay Singh and American Josh Teater, behind outright third Robert Garrigus (10 under) and fourth-placed Bo Van Pelt (nine under).
Americans Bud Cauley and Troy Matteson, along with Colombian Camilo Villegas, round out the top 10 on seven under, four shots off the pace.
Cauley had a day to remember, shooting a seven-under 63, dropping just the solitary shot on 17 after starting on the 10th hole, before storming home with three birdies and an eagle on his back nine.
Coles and Appleby are among a group of six tied for 11th on six under, alongside Americans Patrick Sheehan, Kevin Kisner and Tommy Gainey, and Scotsman Russell Knox.
Nathan Green - the only other Australian to make the halfway cut - is in a share of 39th place at three-under.
British Open champion Ernie Els missed the cut after carding rounds of 72 and 70, while other major champions Jim Furyk, Ben Curtis and David Duval joined local hope Mike Weir in an early exit.