Another pre-race podium favourite, Scott Redding, crashed from his Marc VDS Suter on lap two. The Englishman rejoined, but could only finish 31st on his damaged bike.
Aleix Espargaro (Pons Kalex) and Mika Kallio (Marc VDS Suter), who have stepped down to Moto2 from MotoGP, finished 11th and 20th respectively.
Reigning double World Supersport champion Kenan Sofuoglu began the race from 28th and finished 18th for Technomag-CIP (Suter).
The first ever Moto2 grand prix took place at Qatar just one-year ago, when Sofoglu's Technomag predecessor, the late Shoya Tomizawa, made history as the first ever winner of the 600cc four-stroke grand prix class.
A plaque was unveiled in Tomizawa's honour on Saturday.
Race results- Qatar:
1. Bradl (Kalex) 20 laps
2. Iannone (Suter) +4.330s
3. Luthi (Suter) +5.137s
4. de Angelis (MotoBI) +5.925s
5. Takahashi (Moriwaki) +6.621s
6. Corsi (FTR) +14.217s
7. Cluzel (Suter) +14.257s
8. Pirro (Moriwaki) +14.501s
9. Smith (Tech 3) +18.910s
10. Simon (Suter) +19.174s
31. Redding (Suter) +1m 23.743s
Coghlan (FTR) DNF