Scott Dixon topped the times in the final IndyCar warm-up session in Toronto.
The Ganassi driver's best lap of 59.9117s came in the final minutes of the session, and a late red flag - triggered by HVM's Simona de Silvestro hitting a tyre that had come loose from a barrier in Turn 2 and crashing into the wall - prevented anyone else from being able to better his time.
Simon Pagenaud (Schmidt Hamilton) was closest to Dixon, finishing up just 0.0073s off Dixon's time, with AJ Foyt's Mike Conway and Andretti's Ryan Hunter-Reay just behind him.
It was an eventful session for the American, who needed to pit for a new front wing after missing his braking marker in Turn 3 and running into Penske's Will Power.
Power also needed to visit the pits for a new right rear wheel guard, and eventually ended the session in 11th.
Meanwhile, James Jakes (Dale Coyne Racing) has become the fourth driver to be issued a 10-place grid penalty for an unapproved engine change. James Hinchcliffe (Andretti), Alex Tagliani (BHA) and de Silvestro were already due to be moved down the grid.