"If Ferrari has a fresh engine that has even more power, then that's one or two tenths and it becomes a hard task to keep up with them", said Hamilton. The goal is to make the engine stay the same the whole way through but naturally it's degraded.
"Of course, under the VSC sometimes you benefit and sometimes you lose out - but it was clearly a problem on our side and we need to analyse that to understand what happened and correct it".
"It definitely will have lost performance and so at a power circuit it will probably be magnified".
Hamilton is looking to equal Michael Schumacher's record of seven Canadian Grand Prix wins.
The Scuderia could also face a reduced threat from Red Bull as their vehicle is likely to be less suited on the long straights, though will be strong in the many heavy braking zones.
"There are tracks where each driver has strengths and weaknesses", Hamilton said. "The walls are close and you have to find the rhythm through there to get it right and ride over the kerbs".
Racing begins Friday with two practice sessions, followed by qualifying on Saturday and the race on Sunday afternoon. "And on a track like Montreal, the effects are even greater".
David And Victoria Beckham Address Split Rumours
They also told other outlets that the reports were a "very freaky and an embarrassing waste of time". The Mirror also claimed the rumour was branded "a crock of s***, "embarrassing" and "laughable".
Races for the Canadian Grand Prix runs from June 8-10 at the Circuit Gilles Villeneuve.
It will be a memorable weekend also for two-time champion Fernando Alonso, who is entered for his 300th Grand Prix and, potentially, his 298th start.
And it will feature two Canadians on track - second-year Williams pilot Lance Stroll of Montreal and Nicolas Latifi of Toronto, who will drive a Force India vehicle in the Friday practice only. He is hoping to build on last year's appearance at his hometown track, when as a rookie he earned the first points of his Formula One career. It will be tough to repeat his ninth place finish with the Williams team struggling to get the vehicle up to pace this season.
"We still have work to do", Vettel said.
"Therefore at this point we know that we are not yet where we want to be, because we want to be fastest".
"But it's been very positive in my view".
Bottas played down the delay to the new engine, saying it would have been only "a small gain compared to the old one" anyway. It's a long year. "Hopefully, we can turn things around and pick up more points".