Montreal - Lewis Hamilton bounced back to top the times for Mercedes ahead of championship leader Sebastian Vettel of Ferrari in Friday's opening practice for this weekend's Canadian Grand Prix.
The three-time champion Briton, who is 25 points adrift of Vettel in the title race after a desultory Monaco Grand Prix won by the German, clocked a best lap in one minute and 13.809 seconds to wind up 0.198 seconds clear of his rival.
Hamilton's Mercedes team-mate Valtteri Bottas was third fastest ahead of his Finnish compatriot Kimi Raikkonen in the second Ferrari, Sergio Perez of Force India and his team-mate Frenchman Esteban Ocon.
Dutch teenager Max Verstappen was seventh for Red Bull ahead of Felipe Massa of Williams, Australian Daniel Ricciardo in the second Red Bull and Daniil Kvyat of Toro Rosso.
On a cool and dry morning at the Circuit Gilles Villeneuve, Mercedes were relieved to demonstrate they are back in contention after suffering tyre performance problems in Monte Carlo where Ferrari reeled off a dominant one-two.
The session was littered with minor incidents as most of the field suffered spins and two were forced to withdraw from the fray - Carlos Sainz pulling up with smoke billowing from his Toro Rosso after only one lap and two-time champion Fernando Alonso abandoning his McLaren-Honda with gearbox problems.
Canadian Formula One Grand Prix first free practice times in Montreal on Friday:
1. Lewis Hamilton (GBR/Mercedes) 1:13.809 (36 laps), 2. Sebastian Vettel (GER/Ferrari) 1:14.007 (28), 3. Valtteri Bottas (FIN/Mercedes) 1:14.046 (21), 4. Kimi Rikknen (FIN/Ferrari) 1:14.230 (28), 5. Sergio Prez (MEX/Force India) 1:14.578 (34), 6. Esteban Ocon (FRA/Force India) 1:14.785 (35), 7. Max Verstappen (NED/Red Bull) 1:14.861 (19), 8. Felipe Massa (BRA/Williams) 1:15.106 (31), 9. Daniel Ricciardo (AUS/Red Bull) 1:15.441 (23), 10. Daniil Kvyat (RUS/Toro Rosso-Renault) 1:15.658 (26), 11. Stoffel Vandoorne (BEL/McLaren) 1:15.943 (29), 12. Kevin Magnussen (DEN/Haas) 1:16.233 (25), 13. Lance Stroll (CAN/Williams) 1:16.313 (36), 14. Romain Grosjean (FRA/Haas) 1:16.345 (18), 15. Nico Hlkenberg (GER/Renault) 1:16.473 (27), 16. Fernando Alonso (ESP/McLaren) 1:16.521 (13), 17. Marcus Ericsson (SWE/Sauber) 1:16.805 (24), 18. Jolyon Palmer (GBR/Renault) 1:17.004 (26), 19. Pascal Wehrlein (GER/Sauber) 1:17.606 (28)
Unclassified: Carlos Sainz Jr (ESP/Toro Rosso-Renault) (1)