Ferrari can show that the resurgence is real in Russia
Formula One champions Mercedes have won every Russian Grand Prix since the first at Sochi's Olympic Park in 2014 - but that could all change on Sunday.
Ferrari are on a roll at present, with Charles Leclerc and Sebastian Vettel racking up three wins in a row between them. A fourth will really have the alarm bells ringing at Mercedes headquarters in Brackley and Stuttgart.
Lewis Hamilton, despite being a hefty 65 points clear of Mercedes teammate Valtteri Bottas with six races remaining, has already expressed concern that Ferrari are looking hungrier than the champions.
"If anyone in the team feels relaxed, they need talking to - because we should all be feeling the pain," the Briton said after a strategy error left him fourth in Singapore behind a Ferrari one-two and Red Bull's Max Verstappen.
"These next few races are going to be tough," added the five-time world champion, who won in Sochi a year ago, his third Russian success.
The Black Sea resort circuit has also been good to Bottas in the past, with the Finn taking his first fastest lap in Formula One and first race win there.
"I’ve got some unfinished business in Sochi. It has normally been a good track for me and I need to make sure it will be again," said Bottas, who last year was ordered to move aside and let Hamilton win.
His hopes of settling scores will not have been boosted by Mercedes also making sure he slowed and did not get ahead of Hamilton in Singapore after lapping faster on fresh tyres following his pitstop.
Ferrari have now won on the flat-out speed circuits of Spa and Monza, as well as slow and twisty Singapore. Sochi, different again, offers the chance to show that the resurgence is real.
"It’s another circuit where we’ve come close to winning but never quite managed it," said Vettel, a four-time world champion and to date the only non-Mercedes driver to start on pole in Russia.
"I've started from the front row and in fact two years ago Ferrari locked out the front row, but we really want the satisfaction of taking that last step and winning," said the German, whose Singapore win was his first in 13 months.
Sochi's long straights should suit Ferrari, but the smooth surface makes it a tricky track for drivers to hit the sweet spot with their tyres, while the layout demands a very different aerodynamic set-up to Singapore.
"We have made good progress on our car, especially in terms of our performance on high downforce tracks, and seem to be more competitive on tracks with various layouts now," said Leclerc.
"Time will tell whether we can be as strong here as we have been lately."
Only twice in five years has a driver from outside Mercedes and Ferrari stood on the podium in Sochi. One was Bottas, who finished third with Williams in 2014. The other was Mexican Sergio Perez for Force India (now Racing Point) in 2015.
Verstappen, level on points with third-placed Leclerc in the standings but still 96 points behind Hamilton, was hopeful that he could also be in the mix - even if his car was less suited to the circuit characteristics.
"I’m looking forward to Russia, where there are more overtaking opportunities," said the 21-year-old Dutchman.