Valtteri Bottas beat Lewis Hamilton to take his third pole position in a row and lead a Mercedes one-two in qualifying at the Spanish Grand Prix.
The Finn was 0.634 seconds ahead of Hamilton, who made a series of errors on his first lap before a slower track meant an improvement was impossible on the next.
Ferrari's Sebastian Vettel was third, but his hopes of closing on Mercedes were dashed by a 0.866secs gap to Bottas.
Red Bull's Max Verstappen was fourth ahead of Ferrari's Charles Leclerc.
Bottas means business
Bottas, who leads Hamilton in the championship by one point, set a superb one minute 15.406 seconds on his first run in final qualifying, while Hamilton had a mistake-strewn run.
He had wheelspin out of the final corner starting the lap, then ran wide out of Turn Seven, bouncing over the kerbs on the exit. And then he ran wide again at Turns 12 and 13.
By the time he did his second run, the track was slower, partly because of the gravel that Hamilton himself had deposited on the track in the final sector, and none of the top four improved.
Of the drivers in the top three teams, only Leclerc improved on his final lap, but that was because his qualifying session did not run to plan.
An error on his first run in second qualifying, running wide out of Turn Nine, meant he had to do a second run to progress into the top 10 shoot-out.
That left him short of new tyres, which meant he could only do one run in the final session.
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He opted to do two laps, taking it relatively cautiously on the first to set a 'banker' and then going harder on his second, by which time the tyres would have lost their edge, so matching Vettel was never going to be a possibility.
The 21-year-old ended up 0.316secs slower than his team-mate and 0.231secs down on Verstappen, who is likely to be a thorn in Ferrari's side in the race, as he has proved so often this year.
What they said
Bottas said: "Really enjoyed that. Enjoyed the adrenaline rush you get from those laps. It has started well the season. I feel better and better in the car and I am looking forward to tomorrow."
Hamilton said: "Valtteri did a fantastic job. He has been quick all weekend. On my side, I just didn't put the laps together. Ultimately, it just wasn't a good enough job."
Vettel said: "I just spoke to Valtteri. They were both very happy with the car. For us, a bit more tricky. I got everything out of the car on the first run, the second I had o try something a bit different and it didn't work.
"The car doesn't feel bad but obviously we are not quick enough. Overall, in those sorts of corners you just need the grip and I think we might be a bit down on that."
Hulkenberg pays for a trip to the gravel trap, by trapping his front wing underneath his carAmazing Mercedes
Mercedes, though, look in a league of their own. Their aerodynamic upgrade introduced for this race - which insiders say is worth a gain of 0.4secs a lap - has more than counter-balanced Ferrari's own changes, which also include an upgraded engine.
Mercedes have utterly dominated the weekend and Ferrari look more likely to be in a race with Red Bull for third than with their supposed title rivals for the win.
The top 10 was completed by Red Bull's Pierre Gasly, doing a better job than so far and only 0.351secs from Verstappen, ahead of the Haas drivers Romain Grosjean and Kevin Magnussen, Toro Rosso's Daniil Kvyat and Renault's Daniel Ricciardo.
Ricciardo, who has a three-place grid penalty, had a narrow escape when he only just scraped through into second qualifying in 15th place.
His Renault team have been struggling this weekend, despite a new engine, and team-mate Nico Hulkenberg was knocked out in Q3, after the German went off on his first lap, breaking his only new-specification front wing and having to revert to the older spec.
Hulkenberg just missed out on beating Ricciardo to 15th place.
McLaren's Lando Norris was knocked out of the top 10 by Ricciardo, and he was ahead of Toro Rosso's Anglo-Thai Alexander Albon and the second McLaren of Carlos Sainz, who made a mistake on his final lap and ran wide at Turn 13.
At Williams, George Russell bounced back from a crash in final practice to qualify 19th, nearly 1.2secs ahead of team-mate Robert Kubica.
But Russell will start behind the Pole because of a grid penalty for changing his gearbox after the crash.
Bottas never made it out of the gravel in final practice, but it did not stop him claiming his ninth career poleFerrari have an upgraded engine, aerodynamics... and plenty of work to doPierre Gasly lays down some rubber in his Red Bull
