The title hopes of Charles Leclerc have been dealt another blow with a grid penalty for excessive engine usage.
There will be a 10 place grid penalty for the Canadian Grand Prix because of a third electronics control unit fitted by Ferrari.
Only two electronics units can be used per driver.
After a number of recent problems, Max Verstappen has gained an 80 point swing in favor of Leclerc.
He is currently behind the Red Bull driver in Montreal.
After two victories and a second place from the first three races, Leclerc had a 46 point lead over Verstappen.
There have been two engine failures for Leclerc in the last three races.
He lost the Monaco Grand Prix after a mistake by his team dropped him from the lead to fourth.
He starts the Canadian Grand Prix 34 points behind Verstappen, who was fastest in Friday's practice.
The man who appeared to be the world champion's rival was 0.081 seconds behind.
Carlos Sainz was third fastest in the second car.
At the home race for the team owner Lawrence Stroll, Sebastian Vettel was fourth for the team.
Lewis Hamilton said the Mercedes was the worst car he had ever owned.
The seven-time champion has won the Canadian Grand Prix seven times but he ended the day 13th as Mercedes continued to experiment with set-up ideas and developments in an effort to improve their car.
An experimental floor on my side didn't work and it was similar to every Friday for us.
We don't do much to this car. Different set-ups are being tried by us. We went to different places to see if one way worked or not.
It was a failure for me. It's like the car is getting worse as we try to make it better. We have to build a better car for next year because this is the car for the year.
It's very difficult to use the kerbs because it's so stiff. It's not the place I've been to in my career.
It is a huge battle to keep it out of the wall. When the car leaves the ground, it goes in many different directions.
You are trying to catch a car that jumps and hops. It is difficult. There were some big hits today, but we will raise the car and it won't change anything.
We tried a lot. We have gone and tried something else because those ones don't work. It is expected of this car, we are way off.
Russell said he was concerned about the pace of the qualification in the two cars.
"We're a long way off the pace compared to the front two teams, but also there's a couple of guys who look very strong as well, so we have work to do," Russell said.
We need to make sure we get in. I think the race car will put us in the third best team position, but if we get out of position it will be difficult.