Sebastian Vettel admits Red Bull are lacking single lap pace after finishing outside the top ten in Friday's Italian practice.
The German and his team-mate Mark Webber struggled to match the leading McLarens and Ferraris on Friday afternoon as the sun blazed down on the Monza circuit.
At the end of the 90 minutes, Vettel was down in 13th place, over a second off the pace.
"I think overall we are not as quick as we would like to be, so still some work to do I guess," he admitted.
"I don't know what (Mark) did, I don't know what the others did, but I think we are probably more competitive in race trim.
"But for sure today wasn't as good in terms of true pace. I think you could see we were not quick enough, so a lot to do. So far we ran through our programme and we didn't have any problems.
"There's a lot of work to do but I think the tyres will be good for a single stop in the race.
"I think it looked pretty tight at the top in general. We're a little bit away from that, we need to do a little bit of a step tomorrow, and then we'll see."
Webber, though, didn't fare much better as he ended up P11, 0.814s down on the P1 lap times.
"We are working hard, not quite there yet. A little bit more competitive with fuel in on the long run, but we've got a bit of work to do with the fuel out.
"We're normally not Friday World Champions, so we'll do a bit of work tomorrow.
"Like I say we generally find a good step on Friday. With fuel it's pretty good, short runs, we need to look at it."