REUTERS: Valtteri Bottas put dominant champions Mercedes on top of the timesheets in Friday (Sep 11) practice for the Tuscan Grand Prix, the first Formula One championship race held at Ferrari's Mugello circuit.
Team mate Lewis Hamilton, who leads the Finn by 47 points after eight races, completed the one-two on a sunny afternoon in Italy with a time 0.207 slower.
Red Bull's Max Verstappen, second before lunch, was third and 0.246 off the pace.
"It's been a lot of fun today and I've enjoyed every single lap," said Bottas.
"I think there's still quite a bit of lap time to unlock, both in the car and also as a driver."
Hamilton was equally enthusiastic about the fast and challenging circuit: "There's no time to play around here and it's one of the most physically demanding that I've driven for a while," he said.
"I've been trying to push it to the limit today, but I think there are a few sections where I can improve."
The top six went in pairs, with Red Bull's Alexander Albon fourth fastest and the Renault pairing of Daniel Ricciardo and Esteban Ocon fifth and sixth.
McLaren's Lando Norris became the first crasher of the day in a second session which was twice stopped as drivers tested the limits.
Ferrari's Charles Leclerc had been an encouraging third in the morning, after his team's dismal showing in Belgium and at their home Italian Grand Prix, but was 10th in the second session.
Team mate Sebastian Vettel was 12th and parked up by the side of the track before the end with an apparent engine problem after a spin.
The race is also a celebration of Ferrari's 1,000th championship race with their cars carrying a retro burgundy livery harking back to their debut in 1950.
Bottas lapped with a best time of one minute 16.989 on the soft tyre in the afternoon, after a 1:17.879 in session one.
It was the fifth time in a row that Bottas, who has so far won only the opening race in Austria in July, had been fastest in first practice.
Pierre Gasly, surprise winner at Monza for Red Bull-owned AlphaTauri, was fifth and eighth fastest respectively.
Alfa Romeo's Kimi Raikkonen and Racing Point's Sergio Perez collided late in the second session as the latter was exiting the pits, bringing out red flags again.
Most of the drivers were experiencing the sweeping 5.2 km track - more associated with MotoGP racing - for the first time.
Friday was also the first time paying spectators had attended in a COVID-19-hit season, with 2,800 a day allowed in.