Mercedes driver Lewis Hamilton set a blistering pace in second practice at the French Grand Prix.
The world champion was a massive 0.704 seconds quicker than his closest rival, Red Bull’s Daniel Ricciardo.
Hamilton’s title rival Sebastian Vettel of Ferrari was only fifth fastest, 1.150secs adrift of Hamilton.
The session included a 10-minute red flag period, caused when Sergio Perez’s Force India lost a wheel, which potentially distorted the picture.
The team will investigate how the wheel became detached at around 170mph on the Mistral straight, violently pitching the car into and 180-degree spin.
The delay meant drivers made their qualifying simulation runs at different times, when the track conditions may have been different.
Who has the fastest race pace?
Vettel, for example, set his time on the fastest ultra-soft tyres before the session was stopped, and Hamilton after.
But the race runs also suggested Mercedes had an advantage – Hamilton was about 0.5secs a lap on average faster than Raikkonen on their long runs on the ultra-soft tyres, with Ricciardo behind the Finn.
Neither Vettel nor Verstappen did comparable runs on the same tyre.
The French Grand Prix returns to the calendar for the first time in 10 years, and this is the first race at Paul Ricard in Provence since 1990, when Alain Prost won for Ferrari.
Hamilton heads into the weekend one point behind Vettel in the championship and with an upgraded Mercedes engine which contains both performance and reliability improvements.
The debut of the engine was originally scheduled for the last race in Canada only for Mercedes to postpone it at the last minute when reliability concerns emerged on the test bed.
Since then, Mercedes say they have been able to improve the specification again and it will run in the factory cars and customers Force India and Williams for the rest of the weekend – and presumably the next six races after that.
Vettel said: “Overall, it is not the most exciting track. It is quite tricky here and there. There are some places technically that are quite demanding, the timing needs to be right.
“On one lap it looks like we are a little bit behind. It is understanding what the car needs and what I need to do with the car. I did not put good laps in on one lap so I am not too stressed. We should be fine tomorrow.”
Hamilton’s team-mate Valtteri Bottas had a troubled session. He was just over 0.2secs behind on the first runs – on slower tyres – but then his car suffered a water leak and he had to miss the balance of the session, losing out on both his qualifying run and his race run.
Behind the big three teams, Haas driver Frenchman Romain Grosjean was sixth quickest, sneaking ahead of Bottas, with McLaren’s Fernando Alonso eighth.
The Spaniard, at the French Grand Prix a week after winning at Le Mans with Toyota, may have been flattered in that position by circumstance – he did his quick run on ultra-softs right at the end of the session, when the most rubber would be down to increase grip.
Alonso also had a scrappy session – he ended it with a spin at Turn Three when pushing for a faster time – shortly after a frustrated message to his team over the radio – and had earlier run wide twice at Turn Two.
His team-mate Stoffel Vandoorne was down in 13th.
The second Haas of Kevin Magnussen was ninth fastest, ahead of Frenchman Pierre Gasly in the Toro Rosso.