By Alan Baldwin
BAKU (Reuters) - Valtteri Bottas was fastest for Mercedes in first free practice for the Azerbaijan Formula One Grand Prix on Friday, while Max Verstappen crashed his Red Bull a day after promising to exercise more control.
Bottas's four times world champion team mate Lewis Hamilton was fourth quickest around the Caspian shore street circuit, also on the ultrasoft tyre.
Red Bull's Daniel Ricciardo, winner of a chaotic race in Baku last year, was a mere 0.035 of a second off the Finn's best lap of one minute 44.242 seconds on the slower supersoft Pirelli tyres.
Verstappen, the Australian's 20-year-old team mate, continued an unfortunate sequence of events by skidding sideways into the tyre wall with 55 minutes remaining. Red Bull said the car was not seriously damaged.
The Dutch driver, whose season has been littered with collisions, ended up sixth fastest but still quicker than Ferrari's championship leader Sebastian Vettel who was 10th but without setting a representative time.
The German, winner of the first two races, was 2.2 seconds off the pace.
Team mate Kimi Raikkonen, 15th fastest, spent much of the session in the garage with Ferrari working on a power unit problem.
Mexican Sergio Perez was third for Mercedes-powered Force India, 0.833 slower than Bottas, with French team mate Esteban Ocon fifth in a promising sign for a team with only one point so far this season.
Williams, the only team yet to score, also showed signs of improvement with Russian Sergey Sirotkin eighth.
Vettel leads Hamilton by nine points in the championship, with the Briton still chasing his first win since last October's U.S. Grand Prix.
Verstappen, who collided with Vettel in China two weekends ago in a race the Dutchman could have won, had told reporters in Baku that he planned to drive faster but with more control in future.
That resolution was immediately tested when he locked up while braking, with the virtual safety car then deployed as the car was retrieved.
Verstappen remained a spectator for the rest of the sunny afternoon session.
(Reporting by Alan Baldwin, editing by Jon Boyle)