For those who have followed the 2017 Formula One season, it will be no surprise to learn that the Canadian Grand Prix will be a one-stop race. However, there is some variation in strategy options and once again the undercut (or overcut) could be crucial to the end result.
The question facing the teams with drivers in the top ten is whether to use their single pit stop to switch to super-softs or to softs. The decision will ultimately hinge on temperatures, as the super-soft is a low working range tyre and the soft -- although slower -- is a high working range tyre more suitable to the temperatures forecast for Sunday.
The difference in performance between the super-soft and ultra-soft isn't huge. Friday's running showed -- new tyre for new tyre -- that the super-soft was 0.8s slower than the ultra-soft while the soft was 1.0s slower than the ultra-soft (Pirelli didn't have representative data from the same part of a session to do a direct comparison between super-soft and soft). That suggests that the performance loss of going to the soft over the super-soft will be marginal and, combined with a hot weather forecast, it is no surprise to see Pirelli suggest spending the majority of the 70-lap race on the more durable soft.
So that leaves the question of whether someone will be able to perform an overcut -- as Sebastian Vettel did in Monaco -- by looking after their ultra-soft tyres from the start and waiting for their rival to blink first and switch to the slower softs. The key will be looking after the rear tyres, which are prone to overheating as drivers get on the power out of slow corners. In Friday practice, the furthest anyone went on heavy fuel on the ultra-softs was 14 laps, meaning anyone attempting an overcut will be taking the compound into unknown territory.
The Friday practice runs also suggested there was very little to choose between Ferrari and Mercedes on long runs, meaning a botched pit stop or poor strategy call could decide the race.