Lewis Hamilton set the pace in second practice at the British Grand Prix as team-mate Nico Rosberg hit trouble.
Rosberg, the world championship leader, failed to do a single lap as his car suffered a water leak.
Red Bull's Daniel Ricciardo was second, 0.391 seconds off Hamilton and 0.235secs ahead of team-mate Max Verstappen.
Ferrari's Sebastian Vettel and Kimi Raikkonen were next, with McLaren's Fernando Alonso in a surprise sixth.
British Grand Prix qualifying and the race will be live on the BBC Sport website and radio 5 live Sports Extra. Rosberg's problems, which put him on the back foot heading into qualifying on Saturday because of a lack of preparation time, come against a backdrop of internal tension at Mercedes following the collision between the two drivers on the final lap of last Sunday's Austrian Grand Prix.
Hamilton and Rosberg have been told they are on their "final warning" and that "financial and sporting penalties" could follow if they crash together again.
Rosberg has an 11-point advantage over Hamilton after he dropped from first to fourth following his ill-fated attempt to defend against the world champion at Turn Two at the Red Bull Ring.
Hamilton went on to win the race and Rosberg was penalised by stewards after being found at fault for the incident.