Fernando Alonso has admitted that his Sepang practice performance was hampered by an ear infection.
The former world champion has been unwell since arriving in Malaysia, and limited his mileage to just 32 laps today, taking 15th and 16th places in the two sessions.
"We tried not to do too many laps today as I wasn't feeling one hundred percent," said Alonso.
"It's a very demanding weekend in terms of the heat because we sweat so much, but it was important that we still got enough information.
"Hopefully I will recover more this evening and feel better tomorrow so that I can give my maximum in qualifying, which I think will be one of the most important parts of this weekend, so we need to be ready for that."
Alonso's team-mate Nelson Piquet went off the road in the morning due to a wheel problem, but finished 10th fastest in the afternoon.
"We had a good first day with no major problems and so things look a bit better than they did in Melbourne," said Piquet.
"There is still a lot of work to do, but I'm happy we improved the car between the two sessions."
The team's engineering director Pat Symonds agreed that Renault was in better shape in Malaysia despite its underwhelming positions.
"For the rest of the weekend we have to improve our performance from Australia and early indications are that we can," he said.