Daniel Ricciardo admitted that Red Bull lacked consistency during Fridays' free practice in Sochi.
"It was all right. I think we had some good signs throughout the day," he told Sky Sports F1 after the end of the second session.
"Sort of little peaks and some little drops. We'll obviously look at the peaks and be happy about those.
"We probably just lacked consistency run-to-run," he added. "But I felt that when we were going, we were going alright."
This weekend's Russian Grand Prix is the last outing for this version of the RB13, with major upgrades planned for the B-spec car in Spain.
Ricciardo acknowledged that in the meantime the team was somewhat 'treading water'.
"In terms of us here, we know this is what we've got so we're obviously trying to do what we can with the current car and package.
"But we're not expecting anything too much this weekend. We'll try and do what we can, get the job done, and then hopefully fight for a bit more in a few weeks.
"We have never been very successful on this track in recent years, so saying we will do better than a fifth place Sunday would make no sense," he added.
"I'm not pessimistic, I'm just trying to be realistic, and the Williams have been competitive on this circuit in the past, and they were already competitive in Bahrain two weeks ago. "
"We could be fighting with the Williams for fifth place, but we can not compete with Ferrari and Mercedes, both teams are out of reach this weekend. "
GALLERY: All the pictures from Friday in Sochi
Keep up to date with all the F1 news via Facebook and Twitter
