Some light spots of rain in the afternoon temporarily slowed the pace, but it was never enough to dampen the surface and the usual flurry of fast laps ensued in the final 10 minutes of the hour-long session.
Bezzecchi's time of 1:28.533s handed the VR46 Ducati rider the advantage by 0.044s from Maverick Vinales, with Francesco Bagnaia – who leads the standings by 41 points – third quickest on the Lenovo Ducati, 0.288s down on Bezzecchi at a track where Ducati riders have won seven of the nine MotoGP races held since 2016.
With concerns over the weather, a number of riders fitted soft tyres in pursuit of an early fast time.
Bagnaia, eighth in FP1 in the morning, was the early pacesetter before Maverick Viñales went top with a 1:29.618s lap on the factory Aprilia.
Brad Binder made a big improvement on the Red Bull KTM as he lapped in 1:29.559s to displace Viñales.
Bezzecchi then upped the ante with a 1:29.450 to lead Binder, before Viñales responded with a 1:29.075 with less than 40 minutes on the clock.
Viñales was setting a hot pace on the factory Aprilia and went close to bettering his benchmark time as he led the way from Bezzecchi, Binder and Bagnaia.
Some light spots of rain began to fall around the course with 25 minutes remaining but it wasn't sufficient to cause any real issues.
Marc Marquez appeared to be struggling with the Honda and ran off the track into the gravel. The 30-year-old showed his old aggression as he pushed for a fast lap on soft tyres and slotted into second place momentarily, before Miguel Oliveira (RNF Aprilia) leapfrogged the factory Honda rider. Marquez's lap, though, was ruled out after he exceeded the track limits.
Marquez was later attempting a time attack when Pol Espargaro got in his way and he was forced to abort his lap with minutes left, potentially costing him a place in Q2. The incident was placed under investigation by FIM Stewards.
Enea Bastianini, who previously set the fastest ever lap at the Red Bull Ring in 2022 in 1:28.772s, was a faller at the Turn 2 chicane and made his way back to the pits. The Lenovo Ducati rider failed to progress to Q2 after ending the session in 16th ahead of Monster Energy's Franco Morbidelli.
The pace increased with less than 10 minutes remaining and Bagnaia clocked the fastest lap of the weekend in 1:28.821s to bump Viñales down to second.
Binder improved to second behind Bagnaia, 0.042s slower, with Viñales holding third ahead of Fabio Quartararo (Monster Energy Yamaha) and Oliveira.
However, Bezzecchi had the final say as the Italian ended day one on top following his record lap, followed by Vinales, Bagnaia and Binder.
Bezzecchi suffered a late technical issue and was given a lift back to pit lane on the back of team owner Valentino Rossi's scooter.
Aleix Espargaro was seventh for Aprilia Racing, half-a-second off Bezzecchi, while Alex Marquez (Gresini Ducati), Quartararo and Oliveira secured the final automatic Q2 spots.
On a tough day for Honda, Takaaki Nakagami (LCR Honda) was 18th with Iker Lecuona (LCR Honda) – deputising for the injured Alex Rins – and Joan Mir (Repsol Honda) 22nd and 23rd.