Sergio Perez topped the times for Red Bull ahead of his team-mate and championship leader Max Verstappen in Saturday's third and final practice session for this weekend's Belgian Grand Prix.
The Mexican driver clocked a best lap of 1 min 45.047sec to outpace the world champion by 0.137 seconds, proving Red Bull's dominance at the majestic Spa-Francorchamps circuit.
Ferrari's Carlos Sainz, who was fastest in Friday’s opening session, was third quickest ahead of Lando Norris of McLaren, Alpine's two-time champion Fernando Alonso and George Russell of Mercedes.
Perez's performance was a boost for Red Bull as both Verstappen and his main title rival Charles Leclerc of Ferrari are among seven drivers set to start Sunday's race from the back of the grid after taking penalties for new power-units.
Leclerc ended up seventh, having spun into a barrier and causing a brief red flag intervention late in the session, ahead of four-time champion Sebastian Vettel of Aston Martin, Esteban Ocon in the second Alpine and Pierre Gasly of Alpha Tauri.
Seven-time champion Lewis Hamilton struggled in his Mercedes and was 12th, one place behind Daniel Ricciardo in the second McLaren, the Australian having announced this week that he is leaving the team at the end of the season.
The session began with Hamilton leading the field from the pitlane on a cool and overcast day in the Belgian Ardennes, but it was Alex Albon who was quickest for Williams after the opening runs.
As the action unfolded, another driver was confirmed as facing a grid penalty, Zhou Guanyu of Alfa Romeo joining the six announced on Friday after taking a change of gearbox.
Remarkably, at this time the Chinese was topping the times ahead of team-mate Valtteri Bottas before Ferrari joined the fray after 27 minutes.
It was not easy to draw conclusions from these laps as most teams were experimenting with race set-ups and tyres, but Perez demonstrated that Red Bull were fast, going top in 1:45.972, signalling they were switching their attention to qualifying preparation.
Ten minutes later, with 18 remaining, Verstappen trimmed that time to go top in 1:45.480 while Mercedes, unhappy with progress, returned to more set-up changes, having made little impact as they sought a set-up compromise for the demanding and historic circuit.
Leclerc suffered a setback with eight minutes remaining when he hit a bump and slithered off into a barrier in the high speed second sector.
His Ferrari was not damaged, other than the loss of a front wing endplate, but the session was red-flagged for five minutes, enabling him to return to the pits
Source: National News Agency