Yuki Takahashi, who has replaced Moto2 world champion Toni Elias at the Gresini Moriwaki team, took control of the second 600cc practice session at Qatar on his very last lap.
After being just 18th quickest in the first session Takahashi, who won one race while riding for Tech 3 last year, snatched the top spot from Scott Redding (Marc VDS Suter) by a mere 0.053sec at the close of the second session.
Session one leader Stefan Bradl was just 0.105sec slower than Takahashi in third for Viessmann Kiefer (Kalex), with triple 2010 race winner Andrea Iannone fourth for Speed Master (Suter).
Thomas Luthi, whose Interwetten team has switched from a Moriwaki to Suter chassis, lapped 0.448 sec slower than Takahashi for fifth, with reigning 125cc world champion Marc Marquez - runner-up to Bradl in the final pre-season test and the first practice session - sixth for the Catalunya Caixa Repsol (Suter) team.
Takahashi's team-mate Michele Pirro was seventh in both sessions, while former MotoGP rider Aleix Espargaro claimed eighth for Pons Kalex and 2010 title runner-up Julian Simon ninth for Aspar Suter.
Claudio Corti (Italtrans Suter) was tenth and the final rider within one-second of Takahashi.
The unique four-night race weekend schedule for this year's Qatar event will see one further Moto2 free practice session on Friday, followed by qualifying and (controversially) the warm-up on Saturday, then the race on Sunday.
Thursday practice (2) - Qatar:
1. Takahashi (Moriwaki) 2m 1.695s
2. Redding (Suter) +0.053s
3. Bradl (Kalex) +0.105s
4. Iannone (Suter) +0.288s
5. Luthi (Suter) +0.448s
6. Marquez (Suter) +0.653s
7. Pirro (Moriwaki) +0.803s
8. Espargaro (Pons Kalex) +0.882s
9. Simon (Suter) +0.925s
10. Corti (Suter) +0.987s
16. Smith (Tech 3) +1.502s
29. Coghlan (FTR) +2.959s