Valtteri Bottas and Lewis Hamilton topped the time sheet for Mercedes in a crash-strewn first practice session for the Emilia Romagna Grand Prix in Imola.

Just 0.041s separated the teammates, with Max Verstappen just 0.017s further back in third, at the end of the one-hour session, which was disrupted by two red-flag suspensions to clean up three crashed cars.

It was an incident-packed first practice at Imola on Friday morning 😮

Here are all the highlights from FP1 🎬#ImolaGP 🇮🇹 #F1 pic.twitter.com/dOSNj3I7zE

— Formula 1 (@F1) April 16, 2021

The first came at the 38-minute mark when Sergio Perez and Esteban Ocon came together entering the Villeneuve chicane.

Perez’s Red Bull Racing car came to rest spun backwards just past the apex with a punctured left-rear tire, while Ocon was able to drive around the stricken car to park his Alpine near the entry to Tosa with damage to his right-front corner.

Onboard replays were not available owing to a central F1 technical problem, but the damage suggested the Mexican had clipped the front of the Frenchman as he attempted a pass down his inside. Red Bull Racing boss Christian Horner suggested afterwards that Perez was on a fast lap and Ocon warming down when the apparent collision occurred.

It was a costly crash for both drivers. Perez is still bringing himself up to speed with the RB16B after joining the championship-contending team this year as its fourth different driver in as many seasons, whereas Ocon was trying out upgraded parts for his former Renault team.

The session resumed for a frenetic final 12 minutes, with most drivers taking to the grippy soft tire for performance runs in the cold conditions. But moments before the session was due to end, Nikita Mazepin dipped his right-rear tire into the gravel exiting the penultimate corner and lost control of his Haas car, spinning backwards and crashing into the wall near pit entry, truncating the session.

Some level of the damage might be written down to the chilly spring conditions in Imola, where the ambient temperature was just 52 degrees F at the start of the hour. The track barely responded to the sunshine or the on-track running and struggled to keep itself above around 74 degrees F.

Several other drivers also found themselves off the track, albeit with less serious consequences. Perez and Mazepin both had offs at the beginning of the session, and later Yuki Tsunoda, Verstappen and Hamilton traversed the gravel in a vain pursuit of grip.

Yuki finds the gravel during FP1 👀

It was a difficult session for the AlphaTauri driver on his return to Imola – he'll be looking to improve when second practice gets under way this afternoon #ImolaGP 🇮🇹 #F1 pic.twitter.com/iBTW0GO2LX

— Formula 1 (@F1) April 16, 2021

All teams also experienced telemetry problems related to the issues restricting the availability of TV replays, with car-to-garage data and radio affected.

Ferrari’s Charles Leclerc also suffered technical troubles that kept him to just four laps for the first half-hour, but the Monegasque responded well in the second half of the session to put his car fourth and just 0.232s adrift of the benchmark.

AlphaTauri’s Pierre Gasly split Leclerc from Ferrari teammate Carlos Sainz in sixth, while Fernando Alonso was seventh for Alpine with his car’s evaluation parts.

Lance Stroll was eighth for Aston Martin ahead of Williams driver Nicholas Latifi, who was lucky to get away with a tank-slapper that took him through the gravel at Rivazza late in the morning.

Daniel Ricciardo completed the top 10 for McLaren, 1.2s off the pace.