Charles Leclerc extended his breathtaking run of pole positions to four races with a supreme performance in Russian GP qualifying - but Lewis Hamilton beat Sebastian Vettel to second on the grid.
Leclerc has become the first Ferrari driver since Michael Schumacher in 2001 to claim four poles in succession and the 21-year-old now has six overall in 2019.
But Ferrari missed out on a front-row lockout for a second successive weekend after an "awesome" final lap from Hamilton split the two red cars for Mercedes.
And in a fascinating additional twist for Sunday's race from 12.10pm, Hamilton will start on the more durable medium-compound tyres for the first stint, whereas the Ferraris are on the faster but more fragile softs.
"I'm so glad it came together - I wasn't expecting to get on the front row, that's for sure. I'm really, really happy with it," said Hamilton, who has won in Sochi in each of the past two seasons.
Although Vettel won in Singapore last Sunday, the four-time champion has now failed to outqualify Leclerc for nine events in a row. Leclerc's pole time of 1:31.628 was 0.425s faster than the sister Ferrari, with Hamilton pipping Vettel by 0.023s.
Vettel, who conceded he "couldn't extract the maximum out of the car", will start third.
Red Bull's Max Verstappen beat Valtteri Bottas to fourth, but drops down to ninth on the grid owing to a five-place penalty for engine changes.
But Alex Albon crashed the other Red Bull in Q1 and will start from the back row at the Sochi Autodrom.
Carlos Sainz was a fine sixth-fastest for McLaren on the day the Woking team announced they are returning to Mercedes power for 2021, with the Spaniard to start fifth as a result of Verstappen's penalty. Lando Norris will line up seventh.
Nico Hulkenberg continued a strong weekend at Renault to beat Daniel Ricciardo by three places, while Romain Grosjean was a standout performer to return Haas to the top 10 for the first time since Spa.
Russian GP Qualifying: Top 10
1. Charles Leclerc, Ferrari
2. Lewis Hamilton, Mercedes
3. Sebastian Vettel, Ferrari
4. Max Verstappen, Red Bull*
5. Valtteri Bottas, Mercedes
6. Carlos Sainz, McLaren
7. Nico Hulkenberg, Renault
8. Lando Norris, McLaren
9. Romain Grosjean, Haas
10. Daniel Ricciardo, Renault
*5-place grid penalty
Leclerc on a roll, but Hamilton in the mix
In his first season at F1's famous, and therefore most scrutinised, team, Leclerc now has two more poles than any other driver in a season which has continued to gather stunning momentum.
"He's stealing all the poles right now!" quipped Hamilton, who now hasn't started at the head of the grid for five races.
Leclerc had appeared the favourite for pole after impressive performances in practice and he quickly confirmed that when it really mattered in Q3.
Opening up with a 1:31.8, three tenths faster than Vettel, Leclerc improved by a further two tenths on the second runs - although he initially rebuked himself over the radio for losing time in the final sector, before being told he had won pole.
"The car felt amazing. It definitely feels great to be back on pole but I don't know if it's the best track to start on pole, the straight is very long after the start," said Leclerc.
"The start will be very important as always, but here probably even more because of the straight length."
While powerful Ferrari will still be the favourites to remain ahead by the end of that long run to Turn Two, Mercedes have widened their strategic options for the longer distance by ensuring both their cars will start on the medium tyre.
"We were fortunate enough to opt for a different strategy," added Hamilton. "It's a long way down to Turn One, which is not always the best for starts on the harder tyre, but I'm going to try and toe the life out of Charles if I get the chance."
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