Formula 1 championship leader Valtteri Bottas set the fastest time before suffering an oil leak on his Mercedes in the opening practice session ahead of the Spanish Grand Prix.

Bottas’ session started in shaky fashion, after he first blocked Max Verstappen at the chicane before initially struggling with understeer and then oversteer at the long right-hander Turn 12.

Overcoming his balance issues, Bottas was able to dethrone Sebastian Vettel from the top of the timesheet with 30 minutes of the session remaining and became the first and only driver in FP1 to dip into the 1m17s.

The Azerbaijan Grand Prix winner sealed top spot with a 1m17.951s benchmark, set on his second timed lap of his soft tyre run.

However, his session was compromised late on when his Mercedes developed an oil leak which led to an engine shutdown. He spent the last 15 minutes of the 90-minute session stuck in the garage.

Verstappen lost even more time than Bottas, also suffering an oil leak which led to his team having to remove the floor of his RB15. He ended up 12th on the timesheet.

Both drivers’ relative time loss was somewhat negated when the session was ended three minutes prematurely.

Lance Stroll dipped his left-hand wheels on the grass on the entry to the fast right-hander at Campsa, losing control of his Racing Point and bouncing across the gravel en route to the barriers. The session ended under red flag.

Sebastian Vettel ended up second, 0.115s behind Bottas while his team-mate Charles Leclerc was third.

Lewis Hamilton, who enters this weekend one point adrift of Bottas in the championship, finished the session in a distant fourth, 0.624s adrift of his pacesetting team-mate.

Hamilton complained during his short run simulation that “tyre prep is terrible,” as he struggled to optimise his rear tyres.

Romain Grosjean finished fifth despite suffering two excursions during the session – first bouncing across the gravel at Turn 7 before also running wide and dipping two wheels off-track at Turn 12.

Home favourite Carlos Sainz Jr finished sixth for McLaren, ahead of Grosjean’s Haas team-mate Kevin Magnussen in seventh.

Red Bull’s Pierre Gasly was eighth with his best time set on the medium tyre, while Daniil Kvyat and Nico Hulkenberg rounded out the top 10.

Hulkenberg’s Renault team-mate Daniel Ricciardo was as high as third on the timesheet after the first 40 minutes, but ended up 11th.

Williams once again occupied the bottom two positions on the timesheet, with Robert Kubica edging team-mate George Russell.

Russell lost a mirror in the closing stages of the session.