McLaren's Lewis Hamilton and Jenson Button admit they are struggling for pace at the Indian Grand Prix.
Hamilton and Button were sixth and seventh fastest in Friday's second practice and nearly a second off Sebastian Vettel's Red Bull.
Hamilton said: "The Red Bulls are just too quick; the Ferrari is very quick.
"I think we are quick enough to be third or fourth, but to beat the Red Bulls we need to change something, gain something with the downforce."
Hamilton was more competitive in the race-simulation runs when drivers run with more fuel in the car to prepare for the race, but even then he was slower than the Red Bulls of Vettel and Mark Webber and Fernando Alonso's Ferrari, who was third fastest.
Alonso, who is battling for the drivers' championship with Vettel, set the fastest high-fuel run overall, although the German did the fastest single lap in race trim.
Hamilton was 0.4 secs slower than Alonso overall and his fastest race-simulation lap was 0.4secs slower than Vettel's.
Lotus driver Kimi Raikkonen set the third fastest race-simulation run.
Hamilton added: "[We're] not quick enough but we had quite a positive long run. But the times [are] looking quite good for the Lotus and even the Red Bulls. I think our race pace is not bad compared to others but qualifying not quick enough yet."
Both drivers said they were struggling to make the tyres work on low-fuel runs, although Hamilton said he thought they could solve that in time for qualifying.
"I don't think we can get to the front of the race. It's very difficult to overtake here, the Red Bulls are very hard to beat but the Ferrari, Red Bull and Lotus are very quick on long runs so position is quite important in qualifying. We have to work on that."
He added: "I'm hoping the Red Bulls were on lighter fuel but if they're not maybe we're in trouble. We have a little time maybe in fuel but not enough. We need to make some changes to try to improve and I'm sure I can make some changes to my driving style."
Button said: "If you look at it, [the long-run pace] is still 0.3secs off a Red Bull which over 60 laps is 18 seconds, so it's still quite a lot.
"There are some pretty quick cars out there over long runs. I think we're more competitive over long runs than short runs - short runs we're struggling to get the tyres working.
"It's a good circuit for overtaking but the aim is still to qualify as high as possible. It's not good and we need to work on it. I don't think we're going to claw back the qualifying pace, but race pace is possible."