Mike Conway was quickest in morning practice ahead of qualifying for the IndyCar Series' Toronto round - despite crashing during the session.
Andretti Autosport driver Conway swapped the top spot with Dreyer & Reinbold's Justin Wilson early on, before setting the 1m00.047s lap that would stand as the best of the hour.
He also caused a full course yellow by sliding into the Turn 8 barriers, but was able to rejoin after repairs and set a similar pace.
Scott Dixon ended up being Conway's closest rival with a time 0.0584 seconds adrift in the top Ganassi car.
Helio Castroneves was the leading Penske driver in third, ahead of KV's Tony Kanaan and Wilson, with Ryan Hunter-Reay (Andretti) filling the top six.
Friday pacesetter Will Power was only 13th for Penske, behind top Canadians Alex Tagliani (Sam Schmidt) and James Hinchcliffe (Newman/Haas).
Pos Driver Team Time Gap 1. Mike Conway Andretti 1m00.0468s 2. Scott Dixon Ganassi 1m00.1052s + 0.0584s 3. Helio Castroneves Penske 1m00.1683s + 0.1215s 4. Tony Kanaan KV 1m00.3029s + 0.2561s 5. Justin Wilson Dreyer & Reinbold 1m00.3629s + 0.3161s 6. Ryan Hunter-Reay Andretti 1m00.3643s + 0.3175s 7. Dario Franchitti Ganassi 1m00.4408s + 0.3940s 8. Ryan Briscoe Penske 1m00.4740s + 0.4272s 9. Graham Rahal Ganassi 1m00.5082s + 0.4614s 10. EJ Viso KV 1m00.5577s + 0.5109s 11. Alex Tagliani Sam Schmidt 1m00.6231s + 0.5763s 12. James Hinchcliffe Newman/Haas 1m00.6372s + 0.5904s 13. Will Power Penske 1m00.6554s + 0.6086s 14. Sebastien Bourdais Dale Coyne 1m00.7396s + 0.6928s 15. Danica Patrick Andretti 1m00.8397s + 0.7929s 16. Marco Andretti Andretti 1m00.9202s + 0.8734s 17. Charlie Kimball Ganassi 1m00.9630s + 0.9162s 18. Oriol Servia Newman/Haas 1m00.9655s + 0.9187s 19. Simona de Silvestro HVM 1m00.9694s + 0.9226s 20. Paul Tracy Dragon 1m00.9786s + 0.9318s 21. Takuma Sato KV 1m00.9857s + 0.9389s 22. Vitor Meira Foyt 1m01.0207s + 0.9739s 23. JR Hildebrand Panther 1m01.0865s + 1.0397s 24. James Jakes Dale Coyne 1m01.8964s + 1.8496s 25. Ana Beatriz Dreyer & Reinbold 1m01.9885s + 1.9417s 26. Sebastian Saavedra Conquest 1m02.2641s + 2.2173s