Kimi Raikkonen says that practice for the Australian Grand Prix was a 'demanding day' as he returned to Ferrari.
Raikkonen was ninth quickest in the first session and seventh fastest in the second session.
"That was a pretty demanding day, because although we managed to complete our programme, it wasn't trouble-free," he said.
"In the first session we lost a bit of time, but that didn't prevent us acquiring enough data to evaluate the overall handling of the car and the Pirelli compounds. This evening there will be a lot of work to do, especially to understand what didn't work and to try and improve for qualifying and the race."
Team-mate Fernando Alonso was fastest in the first session and set the third quickest time in the second session.
"The team did a super job and we had no problems," said the Spaniard.
"The track improved from the first session to the second, with more grip compared to the morning and there was also more wind. Running the soft tyre certainly helped, as the extra grip meant the times came down, but it's impossible to have a clear idea of how competitive we are, because as usual, Friday results don't mean much.
"To know more, we must wait until everyone is running in the same trim."