Valtteri Bottas headed Lewis Hamilton in a Mercedes one-two ahead of Red Bull's Max Verstappen in first practice at the Belgian Grand Prix.

The usual top three in F1 2020 were separated by tiny fractions - Bottas was 0.069 seconds ahead of Hamilton, who had 0.012secs on Verstappen.

Racing Point's Sergio Perez and Lance Stroll were fourth and fifth.

Ferrari's Charles Leclerc, winner at Spa-Francorchamps last year, was 14th, ahead of team-mate Sebastian Vettel.

The long straights of Spa, which has flat-out sections in the first and final thirds of the lap, were exposing the lack of straight-line speed of the Ferrari, a problem this season following engine rule clarifications over the winter.

Mercedes, encouraged to work flat-out on their engine by Ferrari's advantage on the straights in 2019, have made a step forward in this area, although the progress on their chassis outweighs it.

Verstappen, whose Honda engine does not match the Mercedes on the straights, was surprisingly close, but it remains to be seen whether Red Bull can maintain that margin as the weekend goes on.

On race pace at the end of the session, Mercedes appeared to have a significant advantage over Verstappen on the soft tyre.

It was an uneventful session, held under grey skies and in cool temperatures on one of the most demanding and historic tracks on the calendar.

Rain is expected during the afternoon's second practice session, and there is a threat of wet weather for Sunday's race, too.

Behind the top six, Renault and McLaren completed the top 10, with the French team's Esteban Ocon and Daniel Ricciardo seventh and ninth, and McLaren's Carlos Sainz and Lando Norris eighth and 10th.

Alpha Tauri's Daniil Kvyat and Pierre Gasly were next, ahead of Alfa Romeo's Kimi Raikkonen and the Ferraris.

Haas drivers Kevin Magnussen and Romain Grosjean and Alfa Romeo's Antonio Giovinazzi all failed to set a time as a result of technical problems.