Second practice is live on the BBC Sport website from 14:00 BST
Mercedes' Lewis Hamilton headed Red Bull's Max Verstappen and Ferrari's Sebastian Vettel in a tight first practice at the Hungarian Grand Prix.
Hamilton was 0.165 seconds ahead of the Dutchman. Vettel, who set his time with Ferrari's latest aerodynamic upgrade, was just 0.001secs behind the Red Bull.
Red Bull's Pierre Gasly was fourth quickest, 0.449secs off the pace.
Valtteri Bottas missed the entire session when Mercedes had to change his engine after discovering a misfire.
That is a blow to the Finn, who last weekend let a golden opportunity to cut Hamilton's championship lead significantly when he crashed late in the race while the Briton was out of the points at that stage.
As it happened, Hamilton ended up extending his lead by two points when he was promoted from 11th to ninth following the disqualification of both Alfa Romeos.
The lost track time in the first session could be costly for Bottas on a circuit where Hamilton has always been strong and has won six times.
On track, the pace of the Ferraris and Red Bulls was an encouraging start to the weekend where both teams expected Mercedes to be strong because of the car's strong low-speed performance.
There was no repeat of the wet conditions from last weekend's German Grand Prix during first practice
Verstappen, though, had two spins, one at the last corner and one at Turn 12, complaining of rear-end sensitivity in his car.
Vettel and Leclerc both ran Ferrari's upgrade, which includes new aerodynamic shapers in front of the side pods as they chase more downforce, the lack of which has been their biggest weakness this season.
Leclerc started the session with it, while it was fitted to Vettel's after his first run and he used it to set his fastest time.
Leclerc, though, was struggling, complaining the car "didn't feel good" and was down in sixth, behind the Haas of Kevin Magnussen.
Renault's Nico Hulkenberg was seventh, ahead of the McLarens of Lando Norris and Carlos Sainz and Kimi Raikkonen's Alfa Romeo.
Both Racing Point drivers had spins, Lance Stroll on the exit of Turn Six and Sergio Perez at Turn 10 and they ended up 15th and 18th.
Polish fans have flocked to the Hungaroring in support Williams' Robert KubicaBottas spent a frustrating session in the Mercedes garage
