Lewis Hamilton and Mercedes dominated the early running for this weekend’s Italian Grand Prix at the high-speed Monza circuit.
Mercedes used its seven remaining engine tokens in the build-up to the event and they were put to good use, as Hamilton clocked a time of 1:24.670.
Hamilton’s lap proved to be 0.463s quicker than team-mate Nico Rosberg, as he moved ahead after the pair initially lowered each other’s benchmark time.
Ferrari's Sebastian Vettel was the only non-Mercedes driver to get within two seconds of the reigning champion’s time but he still finished the session 1.588s adrift, via a spin at the Rettifilo chicane.
Nico Hülkenberg and Sergio Pérez placed fourth and fifth for Force India, though the German had to make an unscheduled visit to the pits after complaining of a smell of petrol.
Kimi Räikkönen was sixth best for Ferrari, while Daniel Ricciardo was the quickest Renault-powered runner in seventh place.
The newly re-signed Felipe Massa and Valtteri Bottas finished eighth and ninth for Williams, with Massa recovering after a moment through the gravel exiting Ascari.
Pastor Maldonado completed the top 10 for Lotus, ahead of Felipe Nasr, Daniil Kvyat and Marcus Ericsson.
Max Verstappen saved a slide at Parabolica en-route to 14th position, while Lotus reserve driver Jolyon Palmer returned to the E23 Hybrid in place of Romain Grosjean and went 15th.
Carlos Sainz Jr. caused a red flag half an hour into the session when he spun under braking at Parabolica, having earlier complained of gearbox problems in his Toro Rosso.
Fernando Alonso and Jenson Button placed 17th and 18th as McLaren conducted limited running prior to a planned engine change during the session.
Manor Marussia pair Will Stevens and Roberto Merhi completed the order, five seconds behind the leading Mercedes.