Daniel Ricciardo picked up where he left off in last year's Formula 1 rookie testing, topping the timesheets on the opening morning of young driver running at Abu Dhabi.
Driving the all-conquering Red Bull RB6, the 21-year-old set a best time of 1m40.813s, within 1.5 seconds of newly-crowned world champion Sebastian Vettel's pole position time from the weekend.
Ricciardo completed 46 laps during the first half-day of running and his lap was some 1.923s faster than that of Force India tester Paul di Resta, who was concentrating on setting benchmark times for team newcomer Antonio Felix da Costa on a heavier fuel load.
McLaren-contracted Oliver Turvey was third-fastest, two tenths off the quickest F1 debutant, GP2 race-winner Sam Bird. The Briton is running on both days for Mercedes.
Fellow newcomer Jean-Eric Vergne was only two tenths slower. The British Formula 3 champion and Red Bull junior is driving for Scuderia Toro Rosso today and tomorrow. Also showing good pace were Sauber reserve driver Esteban Gutierrez and Mikhail Aleshin, who was driving for Renault as a prize for winning the Formula Renault 3.5 title.
Jules Bianchi made his debut as an official Ferrari test driver, completing 31 laps and setting the eighth-fastest time. He was ahead of Formula 2 champion Dean Stoneman, who did not set a proper lap time until the final hour of running as he focused on aerodynamic runs concentrating on the air flow around the wheel. He eventually got down to a respectable pace and will be given more freedom to set fast times this afternoon.
F3 Euro Series ace da Costa sat out the first few hours while di Resta lapped in the Force India, later emerging and completing 20 laps on his F1 debut.
Behind him came the three new teams, with Williams aspirant Pastor Maldonado the fastest driving for HRT.
The test is being run on the same configuration of the Yas Marina circuit as was used for last weekend's F1 championship finale. All of the teams are using Bridgestone rubber for the two-day test prior to switching to Pirelli for the tyre test that starts on Friday.
The test will run for a further three-and-a-half hours this afternoon.
Pos Driver Car Time Laps 1. Daniel Ricciardo Red Bull 1m40.813s 46 2. Paul di Resta Force India 1m42.736s 28 3. Oliver Turvey McLaren 1m42.933s 47 4. Sam Bird Mercedes 1m43.201s 39 5. Jean-Eric Vergne Toro Rosso 1m43.392s 46 6. Esteban Gutierrez Sauber 1m43.410s 37 7. Mikhail Aleshin Renault 1m43.661s 39 8. Jules Bianchi Ferrari 1m43.894s 31 9. Dean Stoneman Williams 1m44.051s 32 10. Antonio Felix da Costa Force India 1m44.704s 20 11. Pastor Maldonado Hispania 1m46.278s 59 12. Rodolfo Gonzalez Lotus 1m46.910s 48 13. Rio Haryanto Virgin 1m49.439s 21 All timing unofficial