Mercedes is wary of the upgraded power unit Ferrari is expected to use at the Canadian Grand Prix.

Ferrari and Honda have both spent engine development tokens ahead of the Canadian Grand Prix, which should see power output increased this weekend for Ferrari, Sauber and McLaren if they opt to use one of their new upgraded power units. Each car is allowed to use four power units over the course of the season before incurring grid penalties, so use of an upgraded power unit has to be balanced against the overall usage of engine components this year.

Both Ferrari drivers are on their second set of engine components, so the use of upgrades would see them take their third power unit of the season. However, there is nothing stopping the team reverting to one of the earlier-spec power units late in the season on a less power-dependent circuit.

Mercedes is not spending any engine tokens ahead of the Canadian Grand Prix, but will install fresh power units in both cars.

"We will bring new power units to this event, the second units of 2015 for each driver," Lowe explained. "Our first power units were used for six complete race weekends, an incredible achievement by the team at Brixworth that saw both achieve total mileages of over 4,000 km.

"We suspect our competitors may also bring new power units, which this year may be upgraded in-season using development tokens, so it will be interesting to see whether and how the 'balance of power' is shifted this weekend."

Last year both Mercedes suffered an MGU-K failure at the Canadian Grand Prix, forcing Lewis Hamilton to retire with brake failure while Nico Rosberg nursed his car home to finish second behind Daniel Ricciardo. Lowe said reliability is a priority this weekend and, despite victories at five of the first six races, he is not taking victory for granted.

"The Montreal track is hard on the whole car, not just the engine and brakes, so we are concentrating our efforts to get two cars to the finish, something we did not manage last year. We take nothing for granted performance-wise, either; the uniqueness of the track means that there will be a lot to get right if we are to bring home the top prizes."