Daniel Ricciardo says Red Bull lacked consistency with its Formula 1 car across Friday's Russian Grand Prix practice sessions.
Red Bull maintained its early-2017 position as the third-fastest team in F1 behind Ferrari and Mercedes in Sochi practice, finishing Friday with Max Verstappen fifth and Ricciardo sixth.
Verstappen was 1.420 seconds off the pace set by Ferrari's Sebastian Vettel, and the Red Bull drivers know their hopes are limited until a chassis "revamp" arrives for next month's Spanish GP.
Ricciardo was a further three tenths adrift, and said part of Red Bull's issue was run-to-run consistency.
"We had some good signs throughout the day and then some little peaks and drops, we will obviously look at the peaks and be happy about those and then try to figure out why," he said.
"We probably just lacked consistency run to run, but I felt that when we were going we seemed to be alright.
"In terms of us here this weekend we know this is what we have got, so we are trying to do what we can with the current car and package, but we are not expecting anything too much this weekend.
"We will try to do what we can, get the job done and then hopefully fight for a bit more in a few weeks."
The Australian added his form was better on the super-soft tyre rather than the ultra-soft, on both single-lap and long-run pace, with "still a bit of work to do" on the former.
He also conceded that the top two teams were going to be too far ahead again this weekend, with Mercedes' Valtteri Bottas finishing the day 0.670s behind Vettel.
"We are not there yet," Ricciardo said.
"We can still improve more with the car what we have this weekend, but as far as positions go, Ferrari and Mercedes are too fast."
VERSTAPPEN HAD FUEL-PRESSURE PROBLEM
Verstappen's long run and Friday running came to an end early, when his Red Bull lost power and crawled to a halt with 20 minutes remaining.
"The problem we think is the fuel pressure," he said.
"It is a bit of a shame of course, we couldn't really do a long run.
"We need to look at what we can improve tomorrow, this track anyway is not our favourite so we just try to make the best out of it.
"The track doesn't suit us. We are quite a bit down on power, especially here, when you already don't have the downforce you want and then the corners and the straights together, so then that makes it just that bit harder."