Raffaele Marciello topped the first day of GP2's post-season test at Yas Marina for the Trident Racing squad.
This year's European Formula 3 champion hit the front in the evening session of what was his first outing in GP2, setting the outright pace with a 1m49.811s.
Only two drivers - series regular Alexander Rossi and Red Bull junior Carlos Sainz - were able to join him in the sub 1m50s bracket.
The former set the pace for Caterham in the morning session with a 1m49.958s, leaving him more than half a second clear of a chasing pack led by Daniel Abt, Johnny Cecotto and last year's GP3 champion Mitch Evans, who was testing for newly-crowned teams' champions Russian Time.
Rossi's time was ultimately enough to earn him second overall, although Carlin's Sainz ended the evening just nine thousandths of a second down the road.
Sainz's time had kept him top of the evening pile until the final hour, when Marciello improved to end the day at the head of the timesheets.
With the exception of Rossi, all top 10 times were set in that latter session.
Abt - testing for Hilmer - secured fourth overall with a 1m50.120s.
Less than one tenth of a second, meanwhile, covered Cecotto (Lazarus), GP2 race-winner Jolyon Palmer (Racing Engineering), Evans and Arden's Rene Binder.
Will Stevens, who took five podiums in Formula Renault 3.5 this year, secured ninth for MP Motorsport, fractions ahead of fellow FR3.5 podium sitter Andre Negrao, driving for Hilmer.
Among a number of changes for day two are Palmer switching to DAMS, British F3 champion Jordan King coming in at Addax and Sam Bird substituting for Tom Dillmann at Russian Time, the team with which he finished runner-up in GP2 this year.
Morning times Pos Driver Team Time Laps 1. Alexander Rossi Caterham 1m49.958s 22 2. Daniel Abt Hilmer 1m50.608s 20 3. Johnny Cecotto Lazarus 1m50.643s 12 4. Mitch Evans Russian Time 1m50.722s 20 5. Raffaele Marciello Trident 1m50.812s 20 6. Daniel De Jong MP Motorsport 1m51.038s 15 7. Nico Muller Arden 1m51.144s 23 8. Stephane Richelmi DAMS 1m51.152s 20 9. Will Stevens MP Motorsport 1m51.210s 21 10. Rene Binder Arden 1m51.234s 25 11. Simon Trummer Rapax 1m51.515s 23 12. Carlos Sainz Carlin 1m51.536s 20 13. Jazeman Jaafar Carlin 1m51.620s 27 14. Julian Leal Trident 1m51.627s 13 15. Andre Negrao Hilmer 1m51.734s 21 16. Rio Haryanto Racing Engineering 1m51.779s 24 17. Jolyon Palmer Racing Engineering 1m51.966s 21 18. Rodolfo Gonzalez Addax 1m52.056s 13 19. Stoffel Vandoorne ART 1m52.357s 28 20. Arthur Pic ART 1m52.422s 28 21. Artem Markelov Russian Time 1m52.763s 17 22. Sandy Stuvik Rapax 1m52.772s 20 23. Nikolay Martsenko Addax 1m53.419s 18 24. Denis Magulin Lazarus 1m55.231s 20 25. Facu Regalia Caterham no time 1 Afternoon times Pos Driver Team Time Laps 1. Raffaele Marciello Trident 1m49.811s 17 2. Carlos Sainz Carlin 1m49.967s 28 3. Daniel Abt Hilmer 1m50.120s 25 4. Johnny Cecotto Lazarus 1m50.206s 19 5. Jolyon Palmer Racing Engineering 1m50.238s 28 6. Mitch Evans Russian Time 1m50.279s 22 7. Rene Binder Arden 1m50.291s 22 8. Will Stevens MP Motorsport 1m50.392s 26 9. Andre Negrao Hilmer 1m50.411s 26 10. Facu Regalia Caterham 1m50.525s 29 11. Stoffel Vandoorne ART 1m50.538s 23 12. Arthur Pic ART 1m50.547s 26 13. Simon Trummer Rapax 1m50.610s 27 14. Julian Leal Trident 1m50.631s 26 15. Nicol Muller Arden 1m50.634s 20 16. Rio Haryanto Racing Engineering 1m50.712s 24 17. Stephane Richelmi DAMS 1m50.791s 27 18. Artem Markelov Russian Time 1m50.900s 25 19. Rodolfo Gonzalez Addax 1m50.993s 25 20. Daniel De Jong MP Motorsport 1m51.106s 22 21. Jazeman Jaafar Carlin 1m51.261s 22 22. Nikolay Martsenko Addax 1m51.339s 30 23. Sandy Stuvik Rapax 1m51.343s 24 24. Alexander Rossi Caterham 1m52.006s 35 25. Denis Nagulin Lazarus 1m53.510s 24