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Charles Leclerc led a Ferrari one-two in second practice at the Canadian Grand Prix after Lewis Hamilton crashed his Mercedes.
Leclerc and team-mate Sebastian Vettel, who had been lagging behind the Mercedes, leapt to the top of the times on their qualifying simulation runs.
Leclerc edged Vettel by 0.074 seconds, after improving on his second attempt.
Mercedes' Valtteri Bottas was 0.134secs adrift in third. Hamilton was sixth after the crash curtailed his running.
The world champion had been quickest when he lost control in the chicane at Turns Eight and Nine, losing the rear and clouting the concrete wall on the outside of the track.
He managed to return to the pits despite a punctured tyre but the incident damaged his car's floor. Mercedes changed the rear end of the car as a precaution but they were unable to get him out in time to take any further part in the session.
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Hamilton said: "I made a mistake and damaged the car. The boys tried really hard to fix it, but there wasn't enough time.
"I don't remember the last time I missed a whole session before. It's definitely not great to watch the session from the garage. It feels like sitting in the headmaster's office, wishing to be back in class.
"It was an innocent mistake. I was doing multiple laps on the medium tyre and was really trying to find the limit. Obviously I went slightly over. I had a big snap out of Turn Nine and was drifting for a long time, hoping I wouldn't hit the wall. But these things happen. You just have to put it behind straight away you and get back on the horse.
"Luckily Valtteri had a good session today, so there'll be a lot of analysis from that."
Ferrari had looked off the pace throughout first practice and through the first runs of the second session, lagging a second or so behind the Mercedes.
But Vettel went fastest on his first lap on low fuel and soft tyres midway through the session. The four-time champion was just just over 0.1secs quicker than Leclerc after their first laps, but the Monegasque improved on his second while Vettel could only repeat his first lap time.
Vettel said: "Not a great day in terms of tyres because they didn't last very long, the very soft compound.
"Overall it was not so bad but we certainly need to improve if we want to put the car in a good position for the race because we're not the fastest. It might look like that if you look at the one-lap performance but I think there is still quite a reasonable gap to Mercedes."
Mercedes have won all the first six races but Ferrari were expected to be more competitive in Canada because the track's layout - comprised of long straights and slow corners - plays to the strengths of their car.
In that sense, it is similar to Bahrain and Azerbaijan, both of which Ferrari could have won if they had not run into problems.
Red Bull's Max Verstappen, who had been close behind the Ferraris earlier in the session, clipped the wall in the final chicane on his fastest lap, as he lost front grip close behind his team-mate Pierre Gasly. The Dutchman ended up 13th, one place ahead of the Frenchman.
McLaren's Carlos Sainz was a highly impressive fourth quickest, just 0.376secs off the pace and 0.382secs ahead of the Haas of Kevin Magnussen in fifth.
Sainz's team-mate, the British rookie Lando Norris, was 11th.
"I think we had one of the best Fridays of the season but I don't believe we are fourth fastest," said Sainz. "We are behind the top three teams. Tomorrow will be back to reality."
Sainz's strong progress continued on his race-simulation run, which was considerably quicker than Vettel's on the same soft tyre, although all drivers were struggling with overheating and the tyres were losing pace very quickly.
But it was Bottas who set the pace on race-distance lap time. His long run on the soft was just over 0.6secs quicker on average than Sainz, as the drivers and teams struggled to understand how the tyres will behave in race conditions.
Behind Hamilton, Racing Point's Sergio Perez was seventh, ahead of the Renaults of Daniel Ricciardo and Nico Hulkenberg and Perez's team-mate Lance Stroll.
Less than a second covered the top 10 cars - and less than two the top 17.
The other British driver George Russell was 19th, his Williams team well off the back of the field as usual. Russell just under 0.3secs quicker than team-mate Robert Kubica, who did not take part in the first session as his car was being used by reserve driver Nicholas Latifi.
Ferrari's Sebastian Vettel beat Lewis Hamilton's Mercedes to pole position at the Canadian Grand Prix.
It was only the second time in seven races Mercedes have been beaten to pole - the other by Vettel's team-mate Charles Leclerc in Bahrain in March.
Vettel was 0.206 seconds quicker than Hamilton, with Leclerc 0.680secs off.
Daniel Ricciardo was a surprise fourth for Renault after Red Bull's Max Verstappen was caught out by a crash by Kevin Magnussen in the second session.
Hamilton had been quickest on the first runs in the top 10 shoot-out, by nearly 0.2secs from Vettel, but the German four-time champion pulled out a special lap on his final run.
Vettel whooped with delight over the radio as he took his first pole position since last year's German Grand Prix in July.
Leclerc, who had been swapping fastest times with Vettel for much of the weekend and in the first two parts of qualifying, said he struggled with the car when it mattered and did not have an explanation.
Mercedes driver Valtteri Bottas will start sixth after a spin on his first lap and then a scrappy lap on his second attempt.
Magnussen crashed at the 'wall of champions' - the chicane just before the start-finish straight, which put paid to Verstappen's ever more desperate attempts to get through to the third session How are Ferrari suddenly quick again?
Mercedes had said before the weekend that they expected a strong challenge from Ferrari on Montreal's Circuit Gilles Villeneuve.
It was a claim met with scepticism in some quarters but it was founded in an understanding that Ferrari have had a straight-line speed advantage all year - and this track layout rewards that like few others.
Hamilton explained that Ferrari were gaining 0.5secs on the straights on overall lap time; the Mercedes has different characteristics as a car. Their car's strengths are in cornering speed, while the Ferrari has less drag and downforce in addition to the most powerful engine.
The race, though, might be a different matter. Ferrari's straight-line speed advantage is not as pronounced in race trim and a close battle is expected.
However, Mercedes go into the race with concerns after one of their new specification engines, which are fitted to the factory team's cars and those of both customers, failed in Lance Stroll's Racing Point in final practice.
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The story of the day was arguably Ricciardo's brilliant fourth place, and the fact he pipped Red Bull's Pierre Gasly for the position will be especially sweet, after so many questioned the Australian's decision to leave Red Bull for Renault this season.
Ricciardo was 0.008secs ahead of Gasly, as Red Bull were left to rue a strategic error in second qualifying.
Attempting to complete that session on the more durable medium tyre so they could start the race on it - as Ferrari and Mercedes did - Verstappen was not quick enough.
At Renault, Nico Hulkenberg also made it into the top 10 in seventh place, 0.253secs slower than Ricciardo.
He headed the McLarens of Lando Norris and Carlos Sainz - another impressive showing by the 19-year-old British rookie - and Magnussen.
Elsewhere, Anglo-Thai novice Alexander Albon was 14th in his Toro Rosso, two places behind team-mate Daniil Kvyat, and British rookie George Russell made it 7-0 in qualifying against his team-mate Robert Kubica in 19th place in the private Williams battle, Russell 0.776secs ahead.
What they said Sebastian Vettel: "I'm full of adrenaline. You know what, the feeling in the car when it just keeps coming and the feeling - it felt so good. I enjoyed it and I'm very happy and happy for the team over the last few races, it's been very tough."
Lewis Hamilton: "I don't feel disappointment, we gave it everything I had got. They were faster and in the last sector they were killing us, the timing was right, procedures were perfect, we had P1 for a second, but we knew they were quick."
Charles Leclerc: "I don't really know I struggled with the car and with the set-up. I struggled with Q1 so I need to work with that on trying to have the right set up for the final Q3 time. Congratulations to Seb he deserves it and hopefully I'll have a better race from my side tomorrow."
Sebastian Vettel lost victory in the Canadian Grand Prix to Lewis Hamilton after being penalised for dangerous driving against his rival.
The Ferrari driver made a mistake under pressure from the world champion, running wide at Turn Three, and pushed Hamilton wide as he rejoined the track.
Race stewards decided Vettel had rejoined the track unsafely and penalised him five seconds for forcing him off the track.
The Mercedes driver would likely have passed Vettel had he not been blocked.
The move will doubtless lead to a major controversy but Hamilton was clear that he felt Vettel had been unfair.
He said over the radio immediately after the incident: "He's just come back on the track so dangerously."
Vettel complained vigorously, saying: "Where the hell else was I supposed to go? I had grass on my wheels."
Told to stay focused, he said: "I am focused but they are stealing the race from us."
Vettel complained that Hamilton could have gone to the inside but that was inaccurate reading of the situation as it unfolded.
Nevertheless, doubtless many will feel that Vettel should have been excused and the drivers allowed to race.
However, others will see it as yet another error under pressure from Vettel, whose 2018 season unravelled as a result of a series of them and who made another in Bahrain earlier this year, spinning after being passed by Hamilton.
And the stewards may well have used precedent to inform the decision, such as when Red Bull's Max Verstappen was penalised in the same fashion for forcing then-Ferrari driver Kimi Raikkonen off the track in last year's Japanese Grand Prix.
How did it unfold?
Vettel had been in front of the race from the start, after converting his pole position, and led through the pit stops.
But once on to the hard tyres after the stops, Hamilton began to pile the pressure on Vettel.
He rejoined after his stop on lap 29 five seconds behind Vettel and was on his tail 10 laps later.
Hamilton stayed within a second of Vettel for the next nine laps until the key moment.
Vettel made a mistake entering the challenging Turn Three/Four chicane and ran over the grass on the second, left-handed part.
As he rejoined the track, Hamilton went to overtake him around the outside, but Vettel did not leave him a car's width on the outside of the track and the Mercedes driver had to back off.
It cost Ferrari another victory in 2019, a year in which Mercedes have won every race, but in which the Italian team could have had two and possibly three wins out of seven.