Red Bull's Max Verstappen topped first practice at the Dutch Grand Prix as Lewis Hamilton showed encouraging pace for Mercedes to take third.
Verstappen, who is chasing a record-equalling ninth successive victory, delighted his home fans by continuing the dominant form that had seen him open a 125-point lead ahead of Formula 1's summer break.
Fernando Alonso was second in the upgraded Aston Martin, but it was Hamilton in third who appeared most likely to challenge Verstappen, with the seven-time world champion having multiple flying laps interrupted.
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The latter, in which he had set an impressive first sector, was halted by Haas' Nico Hulkenberg crashing at Turn 13, prompting a red flag and seven-minute delay.
Verstappen's Red Bull team-mate and nearest title challenger, Sergio Perez, was fourth, with the team looking to maintain their streak of having won all 12 races this season.
Williams delivered an impressive performance as Alex Albon claimed fifth and team-mate Logan Sargeant took seventh, with McLaren's Lando Norris and Oscar Piastri each slotting in behind them.
Ferrari, who had Robert Shwartzman driving in place of Carlos Sainz in one of their allocated rookie sessions, were well off the pace.
Charles Leclerc finished 16th, more than 1.6s back from Verstappen, while Shwartzman was last among drivers who set a time.
The one car that failed to do that was the Aston Martin Lance Stroll after the Canadian was forced out of the session by a suspected power unit issue.
With the season resuming after a near month-long break, there was plenty of experimentation occurring in the early stages as teams used aids such as flow-vis paint and aerodynamic rakes.
Drivers also had to contend with the sand that had been blown onto the track in the Dutch coastal town, meaning Friday's second session at 3pm is likely to paint a clearer picture of the pecking order going into the weekend.
Sky Sports F1's live Dutch GP schedule
FRIDAY AUGUST 25
12.55pm: F2 Qualifying
2.45pm: Dutch GP Practice Two (session starts 3pm)
4.15pm: The F1 Show
SATURDAY AUGUST 26
10.15am: Dutch GP Practice Three (session starts 10.30am)
12.10pm: F2 Sprint Race
1.15pm: Dutch GP Qualifying build-up
2pm: Dutch GP Qualifying
SUNDAY AUGUST 27
8.55am: F2 Feature Race
12.30pm: Grand Prix Sunday: Dutch GP build-up
2pm: THE DUTCH GRAND PRIX
4pm: Chequered Flag: Dutch GP reaction
5.30pm: Dutch GP highlights
Formula 1 returns after the summer break with the Dutch GP and all sessions will be live on Sky Sports F1 from this Friday. Stream F1 on Sky Sports with NOW for just £26 a month for 12 months. Cancel anytime