He looked on course to go fastest but cuts across the chicane after a moment.
He slots into fifth overall now, 0.250s off the pace. He spent some time in the pit lane after a visor strip got stuck in his brake duct.
Leclerc, Russell, Sainz, Tsunoda, Hamilton, Piastri, Perez, Verstappen, Stroll and Ricciardo.
Hamilton goes for a spin at Acque Minerali but keeps it out of the barrier. No harm done.
A 1m17.094s for Russell now, less than a tenth clear of Sainz.
He sets a 1m17.120s to go top of the order, just ahead of Leclerc. Hamilton completes the top three.
He sets a 1m17.438s to go 0.4s clear of Russell at the top of the timesheets.
Just over 33 minutes on the clock. The Ferrari of Leclerc is now out there on the softs.
Russell, Piastri, Hamilton, Verstappen, Tsunoda, Sainz, Leclerc, Perez, Stroll and Ricciardo.
A technical issue for Albon. He's stopped out on track.
A strong end to the lap from the seven-time world champion allows him to slot into third overall.
Mercedes' early impressive pace continues as he sets a 1m17.909s this time to stay ahead of Verstappen, who is on the softs.
A 1m18.193s for the Mercedes driver puts him 0.039s ahead of Piastri. Verstappen, Perez and Sainz complete the top five.
Verstappen, Perez, Piastri, Hamilton, Russell, Tsunoda, Stroll, Sainz, Ricciardo and Leclerc.
Piastri takes to the top now with a 1m18.986s, less than a tenth ahead of Hamilton.
A 1m19.704s for Russell puts him 0.005s ahead of Hamilton. Verstappen is 0.3s off in third.
18 of the 20 cars are out on track at Imola as they get underway. After back-to-back sprint weekends, it's a conventional format this time.
The first session at Imola is underway!
Oliver Bearman will be driving the Haas in FP1 as he starts his run of sessions for the team. The Ferrari junior is set to drive in six FP1s this year.
Hello everyone and welcome to the Crash.net live blog as we look forward to Friday practice for the Emilia Romagna Grand Prix at Imola.
FP1 gets underway at 12:30pm UK time with a number of teams bringing updates to this race.