George Russell's fairytale week continued after he posted the fastest time in opening practice for the Sakhir Grand Prix.
The British driver, who is racing Lewis Hamilton's world championship winning Mercedes this weekend in Bahrain, finished 0.176 seconds clear of Red Bull driver Max Verstappen, with team-mate Valtteri Bottas fourth.
Hamilton has been ruled out of the penultimate round of the season in Bahrain after he contracted coronavirus.
Russell, 22, who has yet to score a single point in his Formula One career, will start among the favourites to win on Sunday after Mercedes agreed a deal to release him from his Williams contract.
FP1 CLASSIFICATION ⏱️@GeorgeRussell63 tops an official race weekend session for the first time in his F1 career 👀#SakhirGP 🇧🇭 #F1 pic.twitter.com/0ON1IYUmg4 — Formula 1 (@F1) December 4, 2020
Russell could have been excused for showing signs of nerves on his Mercedes debut but the Englishman ended the opening running of the weekend on top.
His appearance here is seen as something for an audition for a drive with the sport's all-conquering team in 2022 and his three-tenth advantage over Bottas in the other Mercedes will have been the start to the weekend Russell would have wanted.
The sport is back racing here in Bahrain, just five days after Romain Grosjean's fireball crash stunned the world.
A different track configuration, already scheduled before Grosjean's accident, is being used, with Russell lapping the 2.17-mile circuit in 54.5 seconds.
Let's get out there 💪 pic.twitter.com/xnXET1Qm2L — George Russell (@GeorgeRussell63) December 4, 2020
Verstappen looked as though he will have the pace to challenge Mercedes with his Red Bull team-mate, Alexander Albon, third in the order. Daniil Kvyat finished fifth for AlphaTauri ahead of Pierre Gasly in the other car.
British driver Lando Norris was 16th for McLaren, while Brit Jack Aitken, making his debut here, finished last of the 20 runners in Russell's Williams.
One spot above Aitken was another debutant, Pietro Fittipaldi. The Brazilian is competing for Haas with Grosjean sidelined following the burn injuries sustained to his hands in last Sunday's terrifying crash.
The second and concluding action of the day begins at 2030 local time.