Sebastian Vettel conceded that Ferrari "didn't get it right" as he managed only sixth place during qualifying for the Spanish Grand Prix.
Vettel had closed to within two-tenths of a second of Mercedes' Nico Rosberg during Saturday morning's final practice session, suggesting Ferrari had the potential to challenge for pole position.
However, Vettel could set only the sixth best time in Q3, 1.3 seconds behind pole man Lewis Hamilton.
"I think every day can be tough but for sure I didn't expect to be that far off, especially because this morning we had a good rhythm," he said.
"I didn't get hold of the car, I didn't get the feeling that I had earlier today, and couldn't nail the laps.
"I don't think that it is a surprise, if you don't get it together here it can be quite costly, and we know this. I think the gap to Mercedes is bigger than it has been all weekend. So clearly we didn't get it right."
Team-mate Kimi Raikkonen was fifth quickest but was also overhauled by Red Bull drivers Daniel Ricciardo and Max Verstappen.
"It was not an easy day: we did our best, but the result is a bit disappointing," he said.
"We seemed to struggle quite a lot in the last sector and I'm not surprised we were losing a lot of time there.
"Before qualifying we made some changes to my set-up and the car felt better, but it was not easy to get the laps that we wanted and make the handling exactly as we desired."