Barcelona - Lewis Hamilton topped the times for a resurgent Mercedes team in Friday's second free practice for the Spanish Grand Prix.
Hamilton, the world championship leader headed the Red Bull pairing after a closely-contested session.
The defending four-time champion set his best time of one minute and 18.259 seconds on a set of 'soft' tyres - rather than the usually faster 'super-soft' tyres - as he regained a competitive edge after team-mate Finn Valtteri Bottas had earlier topped the opening practice times.
Australian Daniel Ricciardo was third-quickest for Red Bull ahead of his team-mate Dutchman Max Verstappen, the two managing to deliver speed without any close contact as they worked to put their collision in Azerbaijan two weeks ago behind them.
This meant that Germany's four-time champion Sebastian Vettel of Ferrari, who trails Briton Hamilton by four points after the opening four races of the season, was pushed down to fourth ahead of Bottas and fellow-Finn Kimi Raikkonen of Ferrari.
Frenchman Romain Grosjean was seventh ahead of his Haas team-mate Dane Kevin Magnussen, Belgian Stoffel Vandoorne of McLaren and Mexican Sergio Perez of Force India.
Hamilton took over at the top of the drivers' standings following his lucky victory two weeks ago, when his rivals all crashed or collided, in Baku, but admitted he was struggling for outright speed - a problem he may have done something to rectify with Mercedes upgrades used on Friday.