It was Mercedes who really shoed their pace in the first practice session for the Italian Grand Prix, a second ahead of the rest of the field.
Early in the session the Mercedes traded fastest laps, Hamilton and Rosberg ahead of a few timed runners as many take the opportunity to use the first part of practice as a testing session.
Rosberg once again went faster going out on the supersoft tyre, going three tenths faster than Lewis Hamilton, before Lewis Hamilton overtaking him by just eight thousandths of a second. The German later smashed it again, for a 1:22.9, two tenths of a second ahead of Hamilton this time.
Ferrari, using up their three remaining engine tokens, with the team limiting their mileage, Raikkonen a second off the leading Mercedes drivers in third. Neither Haas or Sauber would get the upgrades this weekend, with the engine supplier claiming that the other teams are on a different cycle to the main works team.
Force India led the charge behind the two top teams, with Sergio Perez in fifth, with Haas taking the sixth fastest time with Romain Grosjean.
Bottas in the first Williams was in seventh, with Verstappen the first ‘Renault’ powered car in eighth, Gutierrez nineth and Daniel Ricciardo rounding out the top ten.
Jenson Button tested the halo for the first time at McLaren, joining Red Bull and Force India testing the safety device this season. Fernando Alonso was told to drive slowly at the end of the session, with the Spaniard returning to the pits.
Felipe Massa had a boost problem on the Williams losing an hour during the session, making his way on the circuit with 40 minutes remaining. He remained in the second half of the order for the session though.
Alfonso Celis was the only development driver taking a seat in the first practice session, with Nico Hulkenberg sitting out the session and just missing out on a top ten position.
It was Renault that would end up at the bottom of the order, nearly four seconds off the pace.