Hadjar took the second victory of his F2 career with a dominant drive at Albert Park as he skilfully navigated two safety car restarts to win by over six seconds.
But the result carries a significant asterisk, with the stewards set to investigate a start-line incident that saw Pepe Marti and Gabriel Bortoleto retire after only travelling a matter of metres.
Unaware of the fast-starting Marti to his right, Hadjar veered across the track causing contact between the Campos driver and second-placed starter Bortoleto, with the pair making heavy contact with the wall.
For Marti, this was his second opening lap retirement in succession following a collision in the Saudi Arabian feature race. This latest incident would be investigated after the race.
Having beaten pole-sitter Roman Staněk into Turn 1, Hadjar headed the field during the five-lap safety car period to allow for the clear-up operation.
Other early movers included championship leader Zane Maloney, who progressed from sixth to fourth as a result of the two retirements, while Victor Martins, who caused a red flag in qualifying and failed to set a time, leapt from P21 to P13.
For Maloney, this progress was undone on the restart as a snap of oversteer and an off-track moment at Turn 6 saw him swamped on the back straight, dropping to P10.
While Hadjar established a six-second lead, the battle for second reached boiling point on lap 10 as three drivers found themselves off in the gravel at Turn 12. The catalyst was Andrea Kimi Antonelli, who lost the rear of his Prema entry before Richard Verschoor spun in sympathy and made contact with Paul Aron. Only Hitech driver Aron was able to continue as the safety car again bunched the field.
After another four laps of neutralised running, the racing resumed with Hadjar again flying off into the distance as Aron fired himself across the Turn 1 gravel and the DAMS pair of Jak Crawford and Juan Manuel Correra getting too close for comfort – Crawford reporting “Juan went into the side of me.”
A third safety car period was narrowly avoided when Joshua Durksen spun into the gravel after tangling with Oliver Bearman – this another incident that would be investigated after the chequered flag, putting at risk Bearman’s first point of the season.
With Hadjar cruising to a comfortable win, Stanek was able to cling onto second after facing pressure from Kush Maini and latterly, Dennis Hauger.
Hauger eventually took the final spot on the podium after overtaking Maini with two laps to go.
Ruing his qualifying error will be ART driver Martins, who finished seventh but will once again start from the back in Sunday’s feature race.