Ferrari's one-two was probably aided by the fact Lewis Hamilton's contact with the wall which ruled him out of the session after just eight laps. Valtteri Bottas completed FP2 but was forced to record more data.
Throughout the season so far, Ferrari has struggled to get the tyres into the optimum, and according to Vettel, the same is happening in Montreal.
"We struggled again with the tyres, especially in terms of performance over a long run. We will have to work on that in the third free practice session because having a good grid position is vital," Vettel said.
"At the moment, I’d say we’re not the quickest, especially over a single lap, where our main rivals seem to have a slight edge. We lack grip in the slowest corners and I’m still not getting the feeling I want from the car."