World champion and series leader Max Verstappen topped the times for Red Bull in Friday's opening practice at the Canadian Grand Prix.
The Dutchman outpaced nearest rival Carlos Sainz of Ferrari by two-tenths of a second in a dry session run in front of a big crowd, revelling in Formula One's return to the Isle Notre-Dame after a three-year absence.
Two-time champion Fernando Alonso was third quickest for Alpine, ahead of Sergio Perez in the second Red Bull and Charles Leclerc of Ferrari, who was using a rebuilt engine after the team wrote off the unit which failed in Baku as beyond repair.
Leclerc, who has had four consecutive pole positions without winning, was 0.5 seconds off the pace set by Verstappen.
George Russell was sixth for Mercedes, ahead of local hero Lance Stroll of Aston Martin, seven-time champion Lewis Hamilton in the second Mercedes, four-time champion Sebastian Vettel in the second Aston Martin and Daniel Ricciardo of McLaren.
Lando Norris was 12th in the second McLaren, behind Pierre Gasly’s Alpha Tauri, after the team diagnosed an issue on his car.
After heavy rain on Thursday had flooded the pit-lane, Friday's session began under blue skies with warm sunshine and a light breeze as Sainz set the early pace.
The Ferrari driver clocked a marker lap in 1:19.708 around the Circuit Gilles Villeneuve in front of a big crowd.
Sainz was soon displaced at the top of the timescreens by Verstappen, and then Valtteri Bottas of Alfa Romeo before the Dutchman regained the ascendancy only to be usurped by Red Bull team-mate Sergio Perez.
After 20 minutes of action, it was clear Mercedes were continuing to experience difficulties on the fast, bumpy and tight barrier-lined track, Russell running in eighth and Hamilton 11th.
For the luckless Esteban Ocon, there were other problems as his Alpine came into the pits with a blazing front-right brake fire. An errant paper towel was blamed.
After 33 minutes, Verstappen reported a problem with a front wheel and was told to pit, shortly before Sainz lapped in 1:15.441 to go back to the top.
Red Bull boss Christian Horner said he had a rear roll bar problem that was quickly resolved, the Dutchman immediately going top in 1:15.158, two-tenths quicker than Sainz.
After struggling and taking a pit-stop for set-up adjustments, Hamilton bounced back and jumped from 15th to sixth, just seven-tenths shy of Verstappen's time.
Russell followed and improved to fifth as the order reshaped in the closing minutes with Alonso moving up to third ahead of Perez before Sainz narrowly missed driving over a groundhog that had dashed across the track.
Few drivers appeared to be in difficulties with severe porpoising or bouncing during the session.