Celestino Vietti caused an upset by storming to an emphatic victory in the Austrian Moto2 at Spielberg, defying pre-race predictions by both catching and passing hot favourite Pedro Acosta.

A return to winning ways for the Italian, Vietti came from a long way back to claim his first win of the season, beating down a gap of almost two seconds to Acosta at one stage before passing for lead with six laps to go and easing home to victory.

Indeed, on a weekend that has seen Acosta emphasise his burgeoning title winning credentials upon assuming the lead of the overall standings last time out at Silverstone, you'd have been hard pressed to find many willing to bet against the KTM Ajo rider in race trim.

Moreover, Acosta certainly looked in good shape to deliver on those odds during the initial stages of the 23 lap race, the young Spaniard getting the hole-shot from pole position into Turn 1 before steadily multiplying his advantage over a chasing pack led first by Jake Dixon before Ai Ogura took over on lap five.

By lap seven Acosta's advantage has swelled to +1.7secs, thanks in part to Ogura losing time when he fluffed his line into Turn 3 and slipped back into the clutches of Dixon.

At this stage Vietti didn't appear to be in the hunt for victory thanks to a tardy getaway from the front row pushing him onto the back foot. However, after latching onto the tussle for second, Vietti swiftly began to exert some authority, first on Dixon for third on lap nine before getting the better of Ogura for second on lap 13.

With Ogura having already made decent headway in reducing Acosta's lead down to just over a second, Vietti subsequently took the baton to continue that momentum, a task made simpler by Acosta getting out of shape into Turn 2 with seven laps remaining.

That moment all but wiped out Acosta's remaining lead, before the sudden presence of Vietti appeared to unsettle him too. Sensing his opportunity, Vietti quickly pounced into Turn 5-6 as Acosta wandered wide to assume the lead for the first time.

Undeterred, Acosta quickly regrouped and capitalised on the benefit of a reference point to keep Vietti honest, but when a near-miss with his rival's rear wheel at Turn 9 with three laps to go sent him wide, he'd ultimately choose to play it safe and protect his 20 points for second.

As such, Vietti was released to complete the fourth win of his Moto2 career, which in turn marks a first victory for the ex-VR46 Racing team under its current Fantic Racing iteration.

Though not the win many predicted, Acosta still leaves Austria with an extended lead over Tony Arbolino in the overall standings. With the Marc VDS rider down in sixth place, Acosta increases his advantage to 17 points.

Ogura followed in third for his second podium of the season, with Dixon - who ran second initially after a bright start - a lonely fourth on the GasGas Aspar.

Somkiat Chantra rounded out the top five to complete a fruitful afternoon for the IDEMITSU Honda Team Asia squad, ahead of a frustrated Arbolino, Filip Salac, Sergio Garcia and British Moto2 winner Fermin Aldeguer.

In a race of high attrition, among the higher profile riders consigned to an early exit were Aron Canes, Alonso Lopez, Sam Lowes - after a tangle with Darryn Binder - Manuel Gonzalez, Albert Arenas and Joe Roberts.

As such, there were some standout results for lesser fancied riders, with Lukas Tulovic scoring his first Moto2 top ten in tenth place, while Dennis Foggia and Izan Guevara landed new bests in 11th and 13th.

There was also some joy for American Racing as Marcos Ramirez got it off the mark in the teams' standings with a run to 14th, while Rory Skinner landed his best Moto2 result yet in 18th.

Austrian Moto2, Spielberg | Race Results

Sunday | Conditions - Dry, Sunny