Jarno Trulli is concerned that the loss of track time to an engine problem in practice today will harm Lotus' chances in Monaco.
The Italian only managed 13 laps this afternoon due to the issue, and though he underlined that he does not lack Monte Carlo mileage, he said his fledgling team needs all the laps it can get.
"It was a bit frustrating today as I lost time in the garage this afternoon, and didn't really get the chance to push as I'd have liked on track," said Trulli. "The times were coming down but, unfortunately, in Monaco every single minute you lose being on track is going to cost you a little bit throughout the weekend.
"Obviously I'm experienced, so on the driver's side it won't affect me but with the car we still need to find the right setup and the right balance. Despite this, it's good to be here and to see Lotus Racing on track, as I know how much that means to a lot of the fans, and also to see that we continue to improve the car every time we get out on track."
Lotus technical chief Mike Gascoyne said the engine problem itself was not much of a concern.
"The engine in question was a high-mileage unit that reached the end of the line today," he said.
While Trulli had a disappointing second session, his teammate Heikki Kovalainen was the quickest of the new teams' drivers.
"Overall, it was a very good Thursday on track," he said. "As soon as I got in the car on Thursday morning it felt good and throughout the day we've been able to improve it step by step, so we're definitely going in the right direction.
"We ended up pretty close to the car in front and anything can happen here so I'm looking forward to qualifying and the race. I'm really pleased with today's performance and I think everyone in the team can be very happy with the job we're doing."