The duo led the way in the extended second free practice session in Montreal which took place after first free practice had to be abandoned because of CCTV problems.
But in the wake of the performance boost delivered by upgrades at the Spanish GP, the team's form around the Circuit Gilles Villeneuve has raised hopes of a proper challenge again this weekend.
However, both drivers felt that the timing of their low-fuel runs late on in the FP2 session flattered their performance compared to the main opposition.
Hamilton said: "The car didn't feel bad, but I think we definitely have got some work to do.
"[It was] not the greatest but not the worst by far. So, it's feeling pretty decent. It's just bumpy.
"I think everyone's having a struggle with the bumps. I think we have just got to improve our ride control and improve the balance through the corner. I think we will be alright."
Russell explained that although the team had topped the times, it remained unclear just where the genuine pace of Mercedes stacked up against the opposition.
"I don't think we can read too much into the timings obviously. We did our low-fuel qualifying prep towards the end of a session when the track was quicker.
"But I do think that the upgrades we brought to the car in Barcelona have helped the limitations that we probably would have had more of with the old specification of car.
"We need to find out where we're going to be. I think we're still on the tail end, especially in qualifying pace, compared to Ferrari and Aston Martin. Valtteri [Bottas] looked quick, maybe an Alpine too.
"But we always know it comes to us on a Sunday, so that's when it's going to matter. It looks to be wet tomorrow. Let's see what it brings."
With Mercedes now having its third race with its new upgrade package, Hamilton said that he continued to feel encouraged by the step made.
Asked how different things felt out on track, he said: "I can only base it off compared to last year, and it's massively better than last year.
"The rear end is not, necessarily, but overall the car is just a step forward. I do think I'm definitely feeling the improvements that we felt in Monaco."
