Red Bull driver Max Verstappen led the way from Ferrari rival Charles Leclerc as F1's second Sprint weekend of the season got underway at the Austrian Grand Prix.
Verstappen, who won both races held at the Red Bull Ring in 2021, posted a time of 1:06:302 on the Soft tyres to lead Leclerc by two-and-a-half-tenths of a second.
After an encouraging British GP weekend, Mercedes continued to feature towards the top of the timesheets with both cars – George Russell leading their charge.
Sergio Perez rose to fourth late on, having pitted a third of the way into the session after telling his engineer that "we need to go in another direction with the car".
The top five positions were completed by Lewis Hamilton, who lapped a couple of tenths slower than teammate Russell in warm, pleasant conditions.
Result Free practice 1 - Austrian
|Results are being loaded...|
Top 10 covered by a second, red flags disrupt the session
Haas put both cars inside the top 10, with Kevin Magnussen sixth and Mick Schumacher ninth, sandwiching Ferrari's Carlos Sainz and Alpine's Fernando Alonso.
Yuki Tsunoda completed the first half of the order as the final driver to get within a second of Verstappen's benchmark around the short, power-sensitive track.
The one-hour session was red-flagged twice, taking valuable track time away from teams amid an already challenging Sprint weekend format.
Lando Norris initially ground to a halt in the middle sector "with smoke coming from under my feet", restricting him to just 14 laps and the slowest time.
Then, in the closing stages, the action came to a halt again when debris settled on the racing line at the exit of Turn 6.
All cars will enter parc ferme conditions - with set-ups locked in - ahead of qualifying later this afternoon.
F1 Podcast: Ferrari win – but did they botch their strategy again?
RacingNews365.com F1 journalists Dieter Rencken and Michael Butterworth discuss the key topics from the British Grand Prix, including Ferrari's questionable strategy calls.