Nico Rosberg set the pace in second practice in the Spanish Grand Prix as Mercedes team-mate Lewis Hamilton could manage only the third-best time.
Hamilton was held up by a slower car on his best lap – but was already 0.2 seconds down on Rosberg’s lap before the delay.
The world champion ended up 0.719secs slower than Rosberg and behind Ferrari’s Kimi Raikkonen.
Raikkonen’s team-mate Sebastian Vettel was fourth after a scrappy session.
Renault’s Jolyon Palmer suffered a high-speed tyre failure, the cause of which is as yet unknown.
Sunday’s race and Saturday’s qualifying are live on the BBC Sport website, with the race on 5 live and qualifying on 5 live Sports Extra, both from 13:00 BST.
Oh… A Toro Rosso is faster than Red Bull
Max Verstappen was eighth fastest, two places and 0.181secs behind team-mate Daniel Ricciardo on his debut for the Red Bull team following his transfer from the Toro Rosso junior team.
The Red Bull drivers were headed by junior team Toro Rosso’s Carlos Sainz in fifth place as much attention focuses on both of the drinks giant’s teams following the decision to switch Verstappen with Russian Daniil Kvyat.
Kvyat was 15th fastest, 1.2secs slower than Sainz.
Ricciardo and Verstappen were separated by McLaren’s Fernando Alonso, seventh fastest at his home grand prix.
The Spaniard’s team-mate Jenson Button had a troubled day, with problems within the engine system restricting his running and then poor handling when he did his fastest lap, leaving him 0.5secs slower than Alonso.
What’s going on with Hamilton?
Hamilton lagged behind Rosberg both on single-lap pace and on the race-simulation runs later in the session on heavier fuel loads, as Raikkonen ended up 0.254secs slower than Rosberg.
Neither Mercedes driver was especially happy with the balance of their car.
The Briton heads into the weekend determined to try to start clawing back some of the 43-point deficit he has to Rosberg after a troubled start to the season.
Two consecutive failures in the hybrid system of his car in qualifying at the last two races have meant him starting down the grid and losing a bunch of points to Rosberg.
Hamilton also faces the problem of inevitably grid penalties later in the season as a result of going through his five permitted engine parts more quickly than planned.
A new design of MGU-H – which recovers energy from the turbo – fitted to Hamilton’s car this weekend as Mercedes seek to solve their repeating problems means he is now on his third example of that part, with only five permitted for the entire season.
Palmer also had a difficult day. Missing the first session because he had to hand his car to reserve driver Esteban Ocon, the Englishman had done only four laps before his tyre let go on the pit straight when he was approaching 190mph.
Palmer said: “The rear left let go. The car wasn’t feeling fantastic before so we need to get it back and find out what’s going on.”
He did get out for more laps in the last half-hour of the session and was a creditable in the circumstances 0.4secs and three places down on team-mate Kevin Magnussen, who was 14th.
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