Ferrari enjoyed a productive start to its Belgian Grand Prix weekend, with Sebastian Vettel and Charles Leclerc leading the charge in FP1.
Vettel's best lap was a 1m44.574s that cleared Leclerc by 0.214s. The soft-shod red duo preceded Red Bull's Max Verstappen and an impressive Alex Albon, with just a tenth of a second separating the teammates.
Mercedes Valtteri Bottas and Lewis Hamilton were fifth and sixth, with both drivers running exclusively on Pirelli's medium compound. But it was a disrupted session for Hamilton whose running was hindered by a few technical issues.
Spa-Francorchamps' epic track was basking in the sun at the outset on Friday as F1 returned to action after a well-deserved summer break.
Red Bull's Verstappen - a genuine local hero at Spa given the proximity of the Netherlands and the fact that he was born on Belgium - was the first to head out on to the track, under the clamors of an orange sea of supporters.
The slow start to the morning session was marked by an alert in the Merc camp when Hamilton was seen limping on the approach to Pouhon, the Brit complaining over the radio about a sudden loss of power.
Hamilton eventually sped up once gain while teammate Bottas clocked in fastest with a lap in 1m47.535s.
However, the Finn was quickly overhauled by Racing Point's Lance Stroll, but the Canadian himself was dispatched by Renault's Daniel Ricciardo who put down a 1m46.790s.
Thirty minutes into the session, the VSC was activated to clean up debris scattered on the Kemmel Straight. A closer look revealed bits of bodywork originating from Stroll's Racing Point, with the car's engine cover coming off on the approach to Les Combes.
Verstappen popped up at the top of the timescreen with a 1m45.803s. Meanwhile, the Dutchman's new teammate Alex Albon was still getting up to speed with his RB15.
But Red Bull's new recruit's bets effort at that point was good enough for a P3, 0.281s behind Verstappen and Bottas.
An hour into the running, Ferrari's chargers, running on the soft tyre, finally got going with Leclerc and then Vettel setting the fastest time, the German edging his teammate by 0.214s with a 1m44.574s.
It was a laborious first hour for Hamilton whose session was marked by another disruption, with no telemetry readings being sent back to the Mercedes garage from the reigning world champion's W10.
With 20 minutes to go, it was a formation of teammates covering the top six with Vettel, Leclerc, Verstappen, Albon, Bottas and Hamilton. But one noted that the Mercedes pair - contrary to their rivals - had yet to bolt on a set of the soft tyre.
It was a busy final ten minutes but with few improvements overall. The pecking order among the top-six remained unchanged, while Stroll, Ricciardo, Sergio Perez and McLaren's Carlos Sainz rounded off the top-ten.
At the other end of the spectrum, Williams' Nicholas Latifi - replacing George Russell in FP1 - and Roebrt Kubica made up the rear, right behind Kvyat and Pierre Gasly who endured a low-key return to Toro Rosso.