Ahead of today's second session, the air temperature is 13.8 degrees C, while the track temperature is 27.6 degrees.
Valtteri Bottas was quickest earlier, ahead of teammate, Lewis Hamilton and Max Verstappen, the three covered by just 0.058s.
It was a strange session, red-flagged twice and with numerous yellow flags as drivers struggled for grip in the unseasonably cool conditions.
The first red flag followed a clash involving Sergio Perez and Esteban Ocon, while the second was the result of Nikita Mazepin spinning into the barrier as he entered the pitlane.
It was a difficult, messy morning for most, a situation not helped by a major issue with FOM's communications which is affecting the TV images, radio communications and data.
It was a mixed morning for AlphaTauri, Pierre Gasly mixing it with the big boys at the top of the timesheets, while Yuki Tsunoda was sidelined by a power unit issue.
The lights go green and Russell gets things underway, followed by Ocon and Raikkonen.
As more drivers head out it appears that FOM has resolved the data issues, certainly in terms of tyre info. Indeed, the drivers are running a mixture of all three compounds.
During the course of this morning's session, race control announced that drivers exceeding the track limits would have their times deleted after the session. At Turn 9 alone, there were 15 instances involving a number of drivers.
Of the first wave, Leclerc goes quickest (17.076), ahead of Sainz, Stroll, Ocon and Giovinazzi.
Bottas splits the Ferraris with a 17.082, as Gasly goes fourth and Perez fifth.
A 16.940 sees Hamilton go second, ahead of Verstappen (16.999).
Bottas goes top with a 16.468, as Verstappen grinds to a halt at the pitlane exit. "Something broke," he reports.
As Verstappen lifts his visor - the replay suggesting a gearbox issue - the VSC is deployed. The Dutchman climbs from his car, his session over.
Bottas goes quickest in all three sectors, finally crossing the line at 15.551.
A 15.672 sees Hamilton close to within 0.121s of his Mercedes teammate, as Red Bull now has to rely on Perez in terms of data accumulation.
Gasly has his time deleted for running wide in T9, which means the decision to defer deleted times in FP1 was down to the various comms issues.
Following his spin at the end of FP1, Mazepin has yet to appear this afternoon, his team having opted to change his gearbox as a precautionary measure.
Gasly asks his team to check his front-left after running over the kerb at T5.
Ocon goes fourth (16.817) on the soft as Latifi goes fifth (16.823) also on the red-banded rubber.
Indeed, more and more drivers are already switching to the softest compound.
Giovinazzi goes fifth and Stroll sixth, while Ocon improves to seventh.
The AlphaTauri pair go fourth and fifth, Gasly (16.208) leading the way.
Hamilton begins his first flying lap on the softs, but his opening sectors are not impressive. Indeed, he fails to improve.
Elsewhere, Leclerc fails to improve after running wide in the final corner.
Mazepin is finally back on track.
The marshals have got Verstappen's car back into the pitlane, which means the Dutchman could yet appear. There are 27 minutes remaining.
While everyone else looks good on the softs, not so the Mercedes pair. Bottas tried three hot laps but with little success.
With 20 minutes remaining, Bottas heads Hamilton by 0.010s, with Gasly just 0.078s off the pace and Sainz 0.283s.
Mazepin complains of a strange feeling with his car, as the Mercedes pair head out again on used softs, no doubt looking ahead to Sunday.
Ouch! Alonso takes a punishing trip over the kerbs that send shockwaves through the Alpine and its Spanish driver.
With 8 minutes remaining there is still no sign of Verstappen heading out again.
Vettel is seeking a gap as he wants to "feel the car in clean air".
"I'm on ice, I'm on ice," yells Mazepin, as he heads off over the grass following a major lock-up.
Oh dear (again). Leclerc is off and in the barriers at Rivazza. "Sorry guys, I was pushing... quite a bit."
The session is red-flagged and with just a few minutes remaining it will not resume.
Bottas is quickest, ahead of Hamilton, Gasly, Sainz, Leclerc, Perez, Tsunoda, Norris, Giovinazzi and Stroll.
Ocon is eleventh, ahead of Latifi, Alonso, Verstappen, Vettel, Russell, Raikkonen, Ricciardo, Schumacher and Mazepin.
Check out our Friday gallery from Imola, here.
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