Four-time world champion Lewis Hamilton says the Montreal race could prove to be “difficult” due to a delay in Mercedes new engine and Ferrari could have the advantage.

Mercedes recently revealed the PU2 will be delayed due to a quality issue and would be available for the next race of the season. The new engine’s reliability is being tested on the dyno before releasing to all six Mercedes powered cars.

The first edition of the 2018 engine has run six races to date and going another race should not be hard as Mercedes had mentioned its power unit lifecycle is a lot longer than the required limits.

The German outfit was planning to use the new unit for Canada and switch back to the previous one for Hungary since the Hungaroring track doesn’t need a high-performance unit.

The delay in the new engine means a loss of an advantage, plus a drop in performance due to high mileage on the first unit, says Hamilton.

“This is a power circuit, so it was our target, and definitely would have been helpful,” said Hamilton.

“The guys worked as hard as they could, and we had to take the sensible decision to not bring it, which is definitely unfortunate. We have to try and make do without.

“But it will mean our performance is not probably the greatest. It’s the seventh race on the engine, and the goal is to make the engines stay the same the whole way through, so naturally, it’s degraded, you lose horsepower over races.

“If we’re at 7000kms or whatever it is, it definitely would have lost performance. So at a power circuit, it will probably be magnified.”

When asked if Ferrari will have a bigger advantage in the Montreal track, Hamilton said: “Yeah, also particularly if they do bring their upgraded engine. So it might be a difficult weekend.

“All I’m hoping for is reliability. If I’m on the seventh race at a difficult circuit on the engine, I want to see it through. That’s my only concern.

“Naturally I’m still here to win, but as I said, if they’ve got upgrades in their engines, which can be from a tenth to two-tenths, Ferrari are particularly very strong on the straights.

“It will be interesting to see whether we’re able to match that or not. But we’re going to give it everything we’ve got, that’s for sure.”

While Hamilton was worried, his teammate Valtteri Bottas believes the loss of upgrade will be “a small penalty”.

“We were initially expecting to bring the new power unit to this race, which would have been a small gain compared to the old one,” said the Finn.

“We found some issues, so just to be safe we still need to make it perfect and hopefully run it in two weeks.

“For sure the new one would have been a little bit better, but it is not like our old engine is a bad one. It is a good one, and it is still all healthy and it is reliable so there are no concerns on that.

“We also planning to use it again later this year in Budapest, but now instead of that, we will use the new one in Budapest.

“I think it is going to be a small penalty. Obviously, it would have been nice [to have it] but that is how it is.”

Ferrari driver Sebastian Vettel was not worried about the mileage on his existing engine and believes its performance won’t change due to the number of kilometres on the unit.

“We have done a pretty good job, the mileage effect is not so big,” he said. “It’s not like after 2500km you lose a lot of power just because of the mileage. That’s not a big problem for us.”

Vettel believes that even Mercedes won’t have a problem in its performance due to the mileage: “With this family, or generation of engines, I don’t think that’s a big problem.”