Lewis Hamilton set the pace for Mercedes in opening practice for the Hungarian Grand Prix on Friday as teammate Valtteri Bottas was sidelined for the majority of the session by a power unit issue.

Formula 1 drivers' championship leader Hamilton edged out Red Bull's Max Verstappen and Ferrari's Sebastian Vettel by one-tenth of a second at the head of the timesheets through a drizzly FP1 that saw drivers struggle for grip through periods of light rain.

Hamilton was able to get in a best lap time of 1m17.233s in the Mercedes W10, with Verstappen and Vettel separated by just 0.001s in second and third place respectively. Verstappen had two spins through the session, reporting that his Red Bull RB14 car felt "sensitive" on turn-in.

Hamilton was left to lead Mercedes solo through the session as Bottas reported a misfire after his opening installation laps, prompting the team to change the power unit on his car as a precaution for another in its pool. While there will be no penalty for the Finn, he will head into the rest of the weekend with plenty of time to make up.

Pierre Gasly finished fourth-fastest for Red Bull ahead of Haas' Kevin Magnussen in P5, while Charles Leclerc took sixth for Ferrari followed by Renault's Nico Hulkenberg. The McLaren duo of Lando Norris and Carlos Sainz finished eighth and ninth respectively, with Kimi Raikkonen completing the top 10 for Alfa Romeo.

Second practice at the Hungaroring will begin at 2pm BST on Friday.