Charles Leclerc crashed his Ferrari at the end of what had been an impressive second practice session at the Emilia Romagna Grand Prix.
Leclerc had earlier set the fastest lap time of the session, only to lose it for exceeding track limits.
Valtteri Bottas was fastest in the session, just 0.01 seconds quicker than Mercedes team-mate Lewis Hamilton.
Red Bull's Max Verstappen suffered a driveshaft failure early in the session.
Bottas' fastest time was set on the medium tyres, but Hamilton's was on the softs, which are theoretically quicker but on which Mercedes barely found any time.
Leclerc's best lap was 0.2secs ahead of Bottas, before it was deleted because he exceeded track limits at Piratella. The Monegasque driver also looked competitive on his race simulation runs.
After his accident in the closing seconds of the session, Leclerc went on the radio to say to his team: "Sorry, guys. I was pushing. Really hard."
Leclerc, who missed half of the first session because of an engine problem, was one of a number of drivers who lost lap times for running beyond the white line that marks the edge of the track at Piratella, a downhill left-hander and the fastest corner on the track.
The 23-year-old said: "It has not been easy day on my side but the performance has been great for me.
"We didn't do the first part of P1 for a small problem. But the car felt good. Then P2, very competitive. We got our lap time deleted for every small margins in Turn Nine. It is most important not to do that in qualifying.
"But the performance was there too, also the race pace was good. Then I made a mistake and went into the wall but better to do it now than in the race.
"The car feels great. The grip is good and the balance is good and I have quite a bit of confidence in the car so I am looking forward to tomorrow."
Alpha Tauri's Pierre Gasly was third quickest from Ferrari's Carlos Sainz, with Leclerc classified fifth with a lap set later on his soft tyres, when they had lost their edge.
Red Bull's Sergio Perez was sixth fastest, ahead of the second Alpha Tauri of Japanese rookie Yuki Tsunoda and McLaren's Lando Norris.
Despite their strong showing, Sainz said Ferrari were "counting" on Mercedes and Red Bull being at the front in qualifying. "They have an edge on us and they will be quicker," the Spaniard said.
Mercedes looked stronger than they had at the same stage of the first race of the season, when Red Bull appeared to have an obvious advantage.
Hamilton said: "The team have definitely worked really hard to try to understand what happened in the last race where we were weak but the track has also come a little bit more in our direction.
"We started off with a really good set-up and just small tweaks here and there but no major issues. So far, good pace for us.
"I don't think we've seen the best from the Red Bulls. They look like they've had quite messy sessions and it will be interesting to see tomorrow just how quick they are."
Verstappen was classified 14th quickest after losing drive running wide over the kerbs at the second Rivazza corner on his first run of the session. That was the end of his session as the car could not be repaired in time to go out again.
It was a day of incidents on the fast and demanding track, as in the first session Perez collided with Alpine's Esteban Ocon in a misunderstanding over track position, taking both cars out.
And Haas rookie Nikita Mazepin had a spin on his first lap of the session and then a crash at the end, both at the same corner, Rivazza.
Haas changed the Russian's gearbox as a precaution between the two sessions, meaning he missed the first 20 minutes of the second, and when he rejoined the track he complained that the car lacked grip, saying it was like driving on ice.
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