Lotus stand-in Jerome d'Ambrosio says it is difficult to set any targets for this weekend's Italian Grand Prix.
The Belgian has been called up to replace the banned Romain Grosjean for this weekend, but he only has one day of running in the Lotus E20 to his name.
That outing came at May's Mugello F1 test, in wet weather conditions. So d'Ambrosio believes that he will have to make the most of the time he has spent on the sidelines with Lotus to get up to speed.
When asked at Monza what his aims are for the weekend, d'Ambrosio said: "It is a difficult question to answer because I don't have much information to set a position target.
"I need to work with the engineers on the car, stay focused on that, and once that work is done we can hope for something good.
"I don't feel I have had plenty of time in the car, one time in Mugello on a fairly wet track, so it will be good to get more time. But I was really involved with the team so far so I will try to capitalise on that."
The former Virgin racer added that being put in a difficult situation like he is this weekend is all part of being a reserve driver in Formula 1.
"Obviously it has been short notice - Monday really - so it has been a bit of a hectic week for me," he said.
"As third driver is it part of the job to be prepared as best as I can, keep fit and keep up to date as much as I could in case something like this happens."