Max Verstappen topped the timesheets during Free Practice 1 at the Canadian Grand Prix
Verstappen set the pace with a time of 1:15.158, while Carlos Sainz was just over two tenths of a second back in P2.
Fernando Alonso claimed an impressive third, ahead of Sergio Perez in fourth.
Charles Leclerc took P5, and George Russell rounded out the top six.
The times tumbled as the session went on, as the track rubbered in during F1's first visit to Montreal since 2019, given that the 2020 and 2021 Grands Prix were cancelled due to the coronavirus pandemic.
Result Free practice 1 - Canadian
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A busy start and brake problems for some
It was a busy start to the session, with several cars keen to get out on track, perhaps concerned by the prospect of more bad weather after heavy rain hit Montreal on Thursday.
Whilst there were no showers to be seen, Russell complained of gusty conditions early in the hour.
Most drivers started out on the Medium compound, with Leclerc and Alonso amongst the few to try out the Soft tyre, whilst others made the switch later in the session.
There were early problems for Esteban Ocon, whose Alpine suffered a brake fire after only three laps on circuit. He wasn't the only one to experience these kind of issues; the Circuit Gilles Villeneuve is known to be tough on brakes.
Ocon's problem looked to be caused by a paper towel causing a blockage, which his team were able to remove.
Perez and Verstappen were at the top of the timesheets by the halfway point of the session, with Perez continuing to show confidence. Sainz also briefly popped into P1.
Elsewhere, the Aston Martin duo of Stroll and Vettel found themselves up in P3 and P4 at one stage, an impressive start to Stroll's home weekend.
Stroll was also seen sporting flow-viz on his car during the session to gather further data. The team introduced a much-discussed upgrade package at the Spanish Grand Prix.
At the other end of the pack, Haas had a disappointing hour, with Kevin Magnussen finishing down in P20, while teammate Mick Schumacher didn't fare much better in P18.
The session ended in reasonably quiet style due to lots of teams focusing on high-fuel runs, seemingly just in case of bad weather in Free Practice 2.
No 'Wall of Champions' victims – yet
The so-called 'Wall of Champions' didn't claim any victims in FP1, but one champion did come slightly close. Alonso had a light brush with the famous corner of the track, but escaped without any contact.
Elsewhere, at another section of the track, Yuki Tsunoda asked his team to check for damage after kissing the wall. The AlphaTauri driver will start the Canadian Grand Prix from the back of the grid due to taking a new engine, going over his season-allowed limit of power units.
For Valtteri Bottas, the issue was not a wall but another driver, with the Finn unhappy about Pierre Gasly seemingly driving slowly on the racing line ahead of him.
And perhaps the luckiest escape of all in the session didn't come for a car but an animal. A groundhog somehow managed to weave across the track, avoiding several incoming cars in the process.
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