Valtteri Bottas ended qualifying in Sochi just 0.095 seconds shy of poleman Sebastian Vettel , conceding to the Scuderia's current speed advantage.
The Finn out-paced team mate Lewis Hamilton again but the effort just wasn't good enough.
"Well I think it's pretty clear to see from the result, Ferrari was quicker today," Bottas said.
"We were close in the end, but not quite enough.
"To be honest, the whole weekend, they've had the upper hand and been able to extract much more especially from the ultra-soft tyre, and that's where we really struggled yesterday."
Bottas believes Mercedes is still a work in progress with improvements possible by tomorrow when the lead contenders line up on the grid.
"We made improvements for today, but obviously not quite enough still," Bottas added.
"Good team effort to get close, we're on the second row. As always, tomorrow is the day that really counts.
"I think a second row start here is not actually that bad a thing. It's a pretty long run into Turn 1."
GALLERY: F1 drivers' wives and girlfriends
Keep up to date with all the F1 news via Facebook and Twitter
Williams suffered a bruising time on Sunday in Sao Paulo, with Alex Albon unable to…
McLaren team principal Andrea Stella has insisted that the squad has no regrets about their…
On this day in 1989, Williams' Thierry Boutsen secured his second F1 win when he…
Red Bull team principal Christian Horner hailed Max Verstappen’s sensational Sao Paulo Grand Prix victory…
Carlos Sainz was left scratching his head after a disastrous Sunday at the Sao Paulo…
Fernando Alonso braved both physical agony and mechanical challenges in the Sao Paulo Grand Prix,…