Mercedes driver Lewis Hamilton set a devastating pace as he topped the timesheets in first practice for Formula 1's Italian Grand Prix at Monza ahead of team-mate Nico Rosberg.
Reigning F1 world champion Hamilton clocked a 1m24.670s to finish 0.463 seconds clear of his title rival and a massive 1.588s ahead of Ferrari's Sebastian Vettel in third.
It was an impressive performance from Mercedes, which fitted Hamilton and Rosberg's cars with their third engines of the season following an upgrade in which it used all seven of its remaining tokens.
Hamilton was quickest on the first run on the medium tyres with a 1m25.653s, 0.906s faster than team-mate Rosberg, with Vettel 0.057s off the pace.
Rosberg was the first to take his second set and moved to the top of the timesheets, but Hamilton reacted straight away to reclaim first.
The opening half an hour was relatively quiet as most teams daubed their cars with flo-vis paint to gather airflow data.
The session was then red-flagged when Toro Rosso's Carlos Sainz Jr lost the car under braking for Parabolica and slid into the gravel.
Force India continued its recent good form with Nico Hulkenberg fourth and Sergio Perez, fresh from a season's best fifth at the last race in Belgium, fifth.
Kimi Raikkonen, who completed a number of practice starts at the end of the pitlane during the session, was sixth quickest, having spent a lot of time in the garage.
Red Bull's Daniel Ricciardo, who along with team-mate Danill Kvyat will receive a 10-place grid penalty for an engine change, was seventh with Kvyat 12th.
The Williams duo of Felipe Massa and Valtteri Bottas, who announced new deals to stay with the team in 2016 on Thursday, finished eighth and ninth respectively.
Lotus's Pastor Maldonado completed the top 10 with the other Lotus of Jolyon Palmer 15th after covering 28 laps in his eighth first practice appearance of the season.
Sauber's Felipe Nasr was a strong 11th, 2.5s off the pace, two spots ahead of team-mate Marcus Ericsson 13th.
Max Verstappen also had a moment at Parabolica after carrying too much speed into the corner.
The Dutchman ran wide, but kept it out of the gravel and continued. He finished 14th fastest, two tenths clear of Sainz, who failed to get back out on track after his early excursion and ended up 16th.
McLaren ended its session early to carry out an engine change.
The team fitted a ninth engine to both Fernando Alonso and Jenson Button's car for first practice - meaning both drivers get a grid penalty - and will switch to an older unit, as planned, for second practice.
The units will then be changed again following second practice as per the strategy. AUTOSPORT understands there are no problems with any of the engines.
Alonso was 17th quickest ahead of Button, with Sauber's Marcus Ericsson and the Manors of Roberto Merhi and Will Stevens propping up the timesheets.
PRACTICE ONE TIMES:
|4||Nico Hulkenberg||Force India/Mercedes||1m26.612s||1.942s||19|
|5||Sergio Perez||Force India/Mercedes||1m26.730s||2.060s||29|
|7||Daniel Ricciardo||Red Bull/Renault||1m26.922s||2.252s||27|
|12||Daniil Kvyat||Red Bull/Renault||1m27.275s||2.605s||29|
|14||Max Verstappen||Toro Rosso/Renault||1m27.591s||2.921s||27|
|16||Carlos Sainz Jr.||Toro Rosso/Renault||1m27.907s||3.237s||8|