Kimi Raikkonen says a difficult weekend could lie ahead for Lotus after a below-par showing in Friday practice.
The Finn, who goes into the weekend sitting third in the championship standings having scored six podium finishes since his return to the sport at the start of the year, could only post the twelfth quickest time as he struggled for grip on the Singapore streets.
Speaking following the end of FP2, Raikkonen said he expected the team to improve its performance for final practice and qualifying on Saturday, but doubted it would find the two seconds needed to get him towards the sharp end of the grid.
“It wasn't the easiest of days for us today,” he said. “We don't have enough grip for some reason, and we seem to be lacking downforce. It's the same on both tyres; a little bit better when the tyres are new, but still not quite the pace we want.
“I think we can improve for tomorrow but we have to find two seconds to get to the front. I don't think we'll find that much time; but I think we should improve from Friday as we usually do.”
Team-mate Romain Grosjean was slightly quicker but he too suffered with a lack of grip through the two sessions ahead of his return from his one-race ban.
“It feels good to be back on track,” he said. “Our position on the time sheets in the morning was not what we'd have liked and even after FP2 we know there is more performance to be found. The car is basically the same as what we ran in Monaco and Budapest where we were very competitive but we've struggled a bit for grip today.
“The good thing is we understand what we need to do, the team has been working hard to make improvements and I'm sure we'll be stronger tomorrow.”