Hamilton quickest as Mercedes makes ominous start at Monza

Tech Corner: Is Mercedes gaining an oil-burning advantage? (3:38)

Sam Collins joins Jennie Gow to explain how Mercedes may be pushing F1's oil-burning regulations to the limit. (3:38)

MONZA, Italy -- Lewis Hamilton topped the opening practice session of the Italian Grand Prix as Mercedes finished over one second up on title rivals and home favourites Ferrari.

The power-sensitive Monza circuit is likely to favour Mercedes, as the world champions still hold an edge on outright power. Ferrari's performance at the Belgian Grand Prix, where it ran Mercedes close on race pace, raised expectations it can fight for a first home victory since 2010.

Though Friday practice never gives a completely accurate reading of how the weekend will unfold, Hamilton's 1:21.537 easily put him top of the session. Teammate Valtteri Bottas finished 0.4s behind, with championship leader Sebastian Vettel finishing a second adrift of the lead time. Ferrari is celebrating its 70th year this weekend but will hope for a significant improvement as the weekend progresses. Ferrari's hopes of finding one may be muddied slightly by the threat of rain in the afternoon and Saturday morning, which could limit meaningful track time ahead of qualifying.

Kimi Raikkonen finished fourth, 0.04s behind his teammate, ahead of the Red Bull drivers. Daniel Ricciardo and Max Verstappen finished fifth and sixth but both face hefty grid penalties for engine changes made coming into the weekend, so both face the prospect of fighting through the field on Sunday afternoon.

Force India pair Sergio Perez and Esteban Ocon, back in the car for the first time since their collision at the Belgian Grand Prix, which prompted the team to ban them from racing freely in future, took the next two spots. With a Mercedes power unit and both Red Bulls set to be shuffled to the back of the order, Force India faces the prospect of a strong race result if its drivers can avoid colliding again.

Stoffel Vandoorne rounded out the top ten for McLaren, but the team is braced for a brutal weekend at Monza -- a circuit with just six corners and several long straights likely to punish the team's problematic Honda power unit. Felipe Massa finished 11th for Williams, a position which is likely to improve later in the weekend. Williams is hoping to build on Massa's strong finish at the Belgian Grand Prix, which had helped save a weekend which had seen the team linger off the pace.

Carlos Sainz finished 11th for Toro Rosso ahead of Haas' Kevin Magnussen. Magnussen was not initially due in the car for FP1, with his slot meant to go to Ferrari junior Antonio Giovinazzi as part of the Italian's schedule of seven Friday morning sessions with the team this year. However, with the threat of rain later in the weekend, Haas decided to put its regular race driver back in the seat, confirming on social media Giovinazzi would get the lost session back at one of the remaining seasons.

Lance Stroll was 13th for Williams, just 0.021s ahead of Toro Rosso's Daniil Kvyat. Fernando Alonso, who is also set for a big engine-related penalty this weekend, was 15th. Alonso used an upgraded engine in FP1 -- the 3.7 spec -- but ended the session early so the team could re-fit an older engine -- the 3.5 spec -- into his car ahead of FP2.

Romain Grosjean finished 16th for Haas, ahead of Renault pair Nico Hulkenberg and Jolyon Palmer. Sauber's Pascal Wehrlein and Marcus Ericsson took the team's customary position at the foot of the timing screens on a weekend which promises little for the team's year-old Ferrari engine.