Lewis Hamilton says there is more to come from Mercedes at this weekend's Canadian Grand Prix after he topped the second practice session at the Circuit Gilles Villeneuve.
Hamilton was a tenth faster than Mercedes team-mate Nico Rosberg, with the duo comfortably clear of Red Bull's Sebastian Vettel in third.
"It felt pretty good out there today but we've still got improvements to make and there is more to come from the set-up and balance tomorrow," Hamilton said.
"This is quite a technical circuit which is all about the kerbs and apexes; you have to have a car that reacts well to the bumps. You're always trying to find the limit so we're not quite where we want to be yet.
"The Ferraris looked quite close today and the rest of the field seemed closer in general but hopefully not too close! It's very hard to overtake here so pole position is important. Nico looked very quick today as well so I have my work cut out for sure. We'll find out everyone's pace in qualifying tomorrow afternoon so let's wait and see what happens."
Rosberg says he is happier following second practice after initially struggling with brakes.
"This morning, we worked on some different things with the brakes which didn't quite work out so we had to change that this afternoon," he said.
"It was much better for the second session so I'm quite happy now with that. But I'm still a tenth off the quickest time so I'll work hard with our engineers tonight to find that extra pace. It's a unique track here and it's very difficult to hit the kerbs just right."