Ferrari have spent three of their remaining six engine performance 'tokens' in preparation for the Canadian Grand Prix this weekend.

There have been rumours that the Italian team, having struggled for results in the last couple of races, were working on an engine upgrade for Montreal.

Reports suggest that it will be in the form of a redesigned turbo, following problems earlier this season.

Sources in the Italian press say that it will leave Ferrari with just three remaining upgrade tokens for the last 14 races after Montreal.

Ferrari has not confirmed the reports, but in a team preview, engine boss Mattia Binotto said that Montreal is a track "where the engine power is quite important".

Germany's Auto Motor und Sport said that Ferrari may also have prepared a new aerodynamic package for Montreal, possibly involving a shorter nose that recently passed an FIA crash test.