Ryan Williams and Scott Harrington carded matching rounds of 7-under 64 on Thursday to share the lead after the first round of the ATB Financial Classic.
Defending champion Hugo Leon is one stroke off the lead at minus-6. He was joined there by Michael Gligic.
Darren Wallace and Wes Homan are two shots back at 5-under 66 at Windemere Golf & Country Club.
Williams was in the third group out off the 10th tee. He carded birdies on the 11th and 16th. Around the turn, he birdied the first, but gave that stroke right back with a bogey on the second.
The 31-year-old birdied three of four holes from the fourth to jump up the leaderboard. Williams posted his final birdie on the par-4 ninth.
Harrington was in the second group out off the first tee and was on fire from the start. He birdied three of the first four holes.
After a pair of pars, he drained five consecutive birdie chances from the seventh. Harrington moved to 9-under with a birdie on the par-five 13th.
However, he dropped shots at 14 and 18 to slip into a share of the lead.
Last year's runner-up Jose de Jesus Rodriguez carded a 4-under 67. He was joined in seventh place by Nico Geyger, Sebastian Saavedra, Creighton Honeck, Will Strickler, Dodge Kemmer, Joe Panzeri, Riley Wheeldon, Ryan Corbin, Steven Lecuyer and Chan Song.
NOTES: Both Williams and Harrington are looking for their first Canadian Tour victories...Two-time champion Dustin Risdon struggled to a 1-over 72 and is tied for 82nd place.