Valtteri Bottas and Lewis Hamilton put Mercedes comfortably top of the order in the first practice session ahead of Sunday's Spanish Grand Prix.
The Mercedes pair were 0.939s quicker than Red Bull's Max Verstappen, who moved into second in the championship by winning the 70th Anniversary Grand Prix last weekend. The Barcelona event takes place at the Circuit de Catalunya, host of preseason testing earlier this year, meaning the teams have six days' worth of data with this year's cars.
Charles Leclerc and Sebastian Vettel put Ferrari fourth and fifth as both drivers completed a healthy 27 laps. Haas' Romain Grosjean was sixth, although it is unlikely Haas will remain so high up the order this weekend.
The returning Sergio Perez, who missed the two Silverstone rounds due to a positive COVID-19 test, was seventh ahead of Red Bull's Alex Albon, who was 0.9s off teammate Verstappen. Albon's session was not without drama, as his car slowed at one point, forcing the Thai driver to lose some time while the team assessed the problem.
Haas' Kevin Magnussen and Racing Point's Lance Stroll out the top ten. McLaren's Carlos Sainz and Lando Norris finished either side of 12th-placed Esteban Ocon, the highest placed Renault driver. The Alpha Tauris finished either side of Alfa Romeo teammates Antonio Giovinazzi and Kimi Raikkonen. Renault's Daniel Ricciardo was 18th, although he completed 31 laps, ahead of Williams' Nicholas Latifi.
Israeli driver Roy Nissany, taking George Russell's place for Williams during the session as per his contract, spun early on. Nissany finished at the bottom of the order, but was only 0.3s slower than Latifi.