Ferrari arrive in Canada fending off accusations they are favouring Sebastian Vettel in the Formula One title race.
Vettel triumphed in Monaco last time out after team-mate Kimi Raikkonen had qualified on pole, with the Finn leading until the pit stops before the German went on to take the chequered flag.
The manner of Vettel's win led some to suggest the switch had been orchestrated by the team to extend Vettel's lead over Mercedes' Lewis Hamilton.
With Hamilton finishing down in seventh, Vettel's win sent him 25 points clear at the top of the drivers' standings, while Ferrari climbed above Mercedes in the constructors' championship.
Team principal Maurizio Arrivabene insisted this week that team orders would not be issued "until the numbers are clear in one direction or the other", but the story promises to be to the fore during the race weekend in Montreal, particularly with Raikkonen having topped the timesheets in Friday practice.
WHAT WE LEARNED FROM PRACTICE
Raikkonen responded to controversially missing out on victory in Monaco by going fastest in practice, as the Ferraris and Mercedes looked evenly matched.
The Finn posted a quick lap of one minute, 12.935 seconds, ahead of Hamilton in second and third-placed Vettel.
Hamilton's team-mate Valtteri Bottas was fourth fastest but the Red Bull pairing of Daniel Ricciardo and Max Verstappen were hit by engine and gearbox issues respectively.
One thing that did become clear during practice was that Circuit Gilles Villeneuve is unforgiving in cool temperatures, with a high number of spins on show on Friday.
Bottas and Romain Grosjean were among the drivers to spin in FP2, while Raikkonen also lost grip earlier in the day.
Fernando Alonso's return from IndyCar threatened to be an unhappy one until a late lap lifted him to seventh after a hydraulic issue limited his running.
1. Sebastian Vettel (Ferrari) - 129 points
2. Lewis Hamilton (Mercedes) - 104 points
3. Valtteri Bottas (Mercedes) - 75 points
4. Kimi Raikkonen (Ferrari) - 67 points
5. Daniel Ricciardo (Red Bull) - 52 points
1. Ferrari - 196 points
2. Mercedes - 179 points
3. Red Bull - 97 points
4. Force India - 53 points
5. Toro Rosso - 29 points
Afternoon thunderstorms are predicted for Sunday, which would further test the drivers' control of their cars following the issues with grip on Friday.