Daniil Kvyat and Daniel Ricciardo played down Red Bull's pace during practice for the Singapore Grand Prix, after an encouraging second session for the team.
Kvyat set the quickest time while Ricciardo clocked the third best lap, despite being held up by Ferrari's Sebastian Vettel while provisionally on course to go top.
"We expected the car to perform better at this track because it has fewer straights" said Kvyat, who had a fuel systems problem in the opening session.
"This afternoon, it didn’t look bad at all and our pace looks promising. I didn’t do much running in the first session, so it was more of a challenge in FP2 and maybe slightly surprising that I did a quick lap immediately, but I felt comfortable straight away.
"It’s good to be P1 for the first time. However, all the teams will be working hard overnight and we will have to see what the situation is."
Ricciardo says he expects Mercedes and Ferrari to make progress prior to Saturday's qualifying session.
"We’ve had a pretty nice car out of the box at the last few races, because the balance has been right," he said.
"Both free practices today were good for us, we hit a bit of traffic on the Option lap, but we know what we have and I think we are looking good for the weekend.
"Saturday is the important day but I am happy we started off on the right foot in free practice. The car felt strong and as expected is performing well at this track. We will be doing some fine tuning tonight.
"We expect the silver cars and the red ones to turn it up tomorrow, but hopefully we can keep the pace we showed to get up as far the grid as possible."