Next up was the Force India of Sergio Perez and the Ferrari-powered Haas of Romain Grosjean. Valtteri Bottas was seventh for Williams, while in the second Haas car Esteban Gutierrez took ninth to split the Red Bulls of Max Verstappen and Daniel Ricciardo.
Of the frontrunners it was Hamilton who set the ball rolling with 1m 25.124s early on before Rosberg did 1m 24.945s, to which Hamilton replied with 1m 24.123s; all of these times were set on the soft Pirelli tyres.
Subsequently Rosberg went faster - 1m 23.736s on the supersoft rubber, then 1m 23.651s - before Hamilton went ahead by eight-thousandths with 1m 23.643s.
At this early stage however, it was the softs which proved quicker. Rosberg later used them to set the session’s fastest time of 1m 22.959s, as Hamilton rode shotgun with 1m 23.162s.
After their supersoft runs Raikkonen, who had been told that he had restricted mileage, used softs to set the third best time of 1m 24.047s as Vettel improved by just a tenth on them, to 1m 24.307s.
It wasn’t a great morning for Red Bull, who might have expected to be next. Instead, Perez pushed his Force India into fifth with 1m 24.650s as Grosjean, using the new Ferrari motor in his Haas, did 1m 24.763s to pip Bottas on 1m 24.785s. That left Verstappen, down in ninth on 1m 24.982s, as Red Bull’s leading runner.
Ricciardo, on 1m 25.120s, was separated from his team mate by Gutierrez, who made it two Haases in the top 10 with 1m 25.113s.
Jenson Button and Fernando Alonso were 11th and 13th respectively for McLaren, split by test driver Alfonso Celis who did a good job in Nico Hulkenberg’s Force India.
Further back, Esteban Ocon impressed with 18th fastest time for Manor, a second ahead of team mate Pascal Wehrlein, whose DRS later malfunctioned. Alonso also met trouble late in the session, when he toured with his McLaren in stuck in gear.