Sebastian Vettel set a remarkable pace in second practice, moving half a second clear of the field as Mercedes hit problems in Monaco.
The Ferrari driver lowered the lap record on the street circuit, set by Lewis Hamilton in the morning, with a 1m12.720s on his low fuel qualifying simulation, the only driver under the 1m13 mark.
Daniel Ricciardo put Red Bull in position as the closest challengers to Ferrari in second on as Kimi Raikkonen completed the top three in the second Prancing Horse.
The big surprise on Thursday remained the pace of Toro Rosso as both Daniil Kvyat and Carlos Sainz, who only supersoft tyres in the first session, led the first 45 minutes after switching to the ultrasoft, until eventually settling in fourth and fifth respectively.
Max Verstappen had the pace to clear the two fellow Red Bull-backed drivers ahead but hit traffic on his flying laps in the final sector, having to settle for sixth. As Sergio Perez continued his strong start to the weekend in Monte Carlo, taking seventh for Force India.
As mentioned, Mercedes struggled massively for pace throughout the session due to a wrong turn on set-up with both cars. Reaching and maintaining the optimum tyre temperature was the main issue as both drivers had very poor grip in the traction zones, as a result Hamilton was down in eighth with team-mate Valtteri Bottas in 10th.
McLaren had a better session with their two drivers, Stoffel Vandoorne and Jenson Button, setting almost identical lap times in 11th and 12th as Felipe Massa dropped to 13th for Williams. It was his team-mate Lance Stroll, however, who caused the first red flag of the weekend, losing control of the car entering Massanet and hitting the barriers on the outside with half an hour to go.
Romain Grosjean was 14th in the second Haas ahead of fellow countryman Esteban Ocon, who survived an early smack against the Armco at Portier in his Force India.
Renault’s troubles continued as Nico Hulkenberg was only 17th after his ERS issue in the morning, team-mate Jolyon Palmer would also be struck by poor reliability as the Briton stopped out on track early on with a suspected engine failure.
At the back, the two Sauber’s brought up the field with Marcus Ericsson and Pascal Wehrlein separated by just four thousandths of a second.
