Lewis Hamilton finished fastest in second practice for the Canadian Grand Prix as the action finally started in Montreal on Friday.
The opening running of the weekend was abandoned following an embarrassing CCTV failure at the Circuit Gilles Villeneuve. But the problem was fixed to allow an extended 90-minute second session later in the day and it was Hamilton who topped the time sheets with Mercedes team-mate George Russell second.
Carlos Sainz finished third for Ferrari ahead of Aston Martin's Fernando Alonso and Ferrari's Charles Leclerc, while championship leader Max Verstappen ended the day in sixth position for Red Bull.
Hamilton finished runner-up to Verstappen at the last round in Spain a fortnight ago in his revamped Mercedes machine, and the seven-time world champion spoke earlier this week about the grid's once-dominant team having discovered its North Star as they bid to reel in Red Bull.
And the early signs at the eighth round of the campaign were again encouraging at a venue where Hamilton has won on seven occasions - more than any other driver.
The 38-year-old finished 0.027 seconds clear of Russell in the other Mercedes, with Sainz a tenth adrift. Verstappen, who heads the championship order with five victories from seven appearances this year, finished four tenths back.
The second session was brought forward by 30 minutes - and extended to an hour-and-a-half - after the opening running was red-flagged with just four minutes on the board when Pierre Gasly broke down in his Alpine. Only a handful of drivers had posted a lap with Hamilton and Russell among those who had not taken to the track.
The session had been expected to restart as usual following the removal of Gasly's Alpine, but Formula One's governing body, the FIA, blamed "issues with local CCTV infrastructure" for the initial delay.
The suspension in play then became temporary with the FIA confirming at 14.20 local timethat the session would not be resumed leaving an estimated 90,000 spectators short-changed and the sport with red faces.
Two red flags then disrupted the second session after Nico Hulkenberg's engine blew up, and Esteban Ocon broke down in his Alpine on a troubled day for the French team.
Lance goes straight on 😳
— Formula 1 (@F1) June 16, 2023
It's looking awfully wet out there! 🌧️#CanadianGP #F1 pic.twitter.com/baxuewskjR
Dark clouds lingered over the 14-corner track and heavy rain arrived with 10 minutes remaining to cement Mercedes' position at the top of the order.
Rain is forecast for Saturday's qualifying session and could also play a part in Sunday's 70-lap race.