Red Bull’s Max Verstappen was fastest in second practice at the Belgian Grand Prix, with Daniel Ricciardo’s Renault also ahead of the Mercedes.
Lewis Hamilton was third fastest as the top three were separated by only 0.096 seconds.
Mercedes’ Valtteri Bottas was down in sixth, behind Red Bull’s Alexander Albon and Racing Point’s Sergio Perez.
The times are unlikely to be representative of real performance.
Ferrari, in particular, were out of position, with Charles Leclerc 15th and Sebastian Vettel 17th.
The Italian team were always expected to be off the pace around the high-speed Spa-Francorchamps circuit, given their straight-line speed deficit this season, but it is unlikely they will be that slow come qualifying on Saturday.
Even the Alfa Romeos, which have been significantly slower than Ferrari so far this season, were ahead of them in this session, and there is no obvious reason why the form of the two teams, who use the same engines, would have switched so dramatically.
The same is likely to be the case for Mercedes, who have dominated qualifying so far this season and would not be expected to be in third and sixth places.
The fragmented nature of the race-simulation runs made it even harder to divine a clear picture of relative pace.
Hamilton, who leads the championship by 37 points after six races, did only one lap on soft tyres on his race-simulation run before a virtual safety car caused by Ricciardo’s Renault stopping out on track with a loss of hydraulic pressure.
That one lap by the Mercedes was almost identical to the first time set by Verstappen on his race-simulation run.
After that, Hamilton switched to the hard tyre, but managed only one lap on that before the session was stopped because of debris on track from a sponsorship hoarding.
It restarted but only in time for a final seven minutes of running.
Behind Bottas, McLaren’s Lando Norris was seventh fastest, ahead of Renault’s Esteban Ocon, McLaren’s Carlos Sainz and Alpha Tauri’s Pierre Gasly.