Ricciardo put in some impressive times in testing
Red Bull Racing protege Daniel Ricciardo set the pace on the first of two young driver days at the Yas Marina circuit in Abu Dhabi.
The 21-year-old Australian topped the standings just two days after Red Bull's Sebastian Vettel became the youngest Formula 1 champion, aged 23.
The test sessions are designed to give the teams the opportunity to evaluate up-and-coming prospects.
"I think I'm probably as ready as I can be," said Ricciardo.
"We'll try to do a few more long runs, maybe prepare more for a race situation to see how the body holds up.
"I think I've done quite a bit now in the junior categories and now this is my fourth proper day in an F1 car."
Ricciardo's time of one minute 39.616 seconds would have been good enough for third on the grid in Saturday qualifying for the Abu Dhabi Grand Prix.
The Perth driver was last year's British Formula 3 champion.
Venezuela's Pastor Maldonado, who is favourite to take Nico Hulkenberg's vacant race seat at Williams, was in action with the Hispania Racing team and did 108 laps.
Compatriot Rodolfo Gonzales was driving for Lotus.
"It was very good because I adapted immediately to F1 cars," said Maldonado, who will test for Williams on Wednesday.