South Africa's Brad Binder, riding a KTM, won a frantic Argentina MotoGP sprint race on Saturday ahead of Ducati duo, Marco Bezzecchi and Luca Marini of Italy.
World champion Francesco Bagnaia, on a factory Ducati, was only sixth after sweeping the sprint and the showpiece grand prix at last weekend's season-opener in Portugal.
However, the Italian retains the championship lead ahead of Sunday's main race where he will look to deliver Ducati's first victory at Termas de Rio Hondo.
Alex Marquez, of Ducati-Gresini, will start Sunday's grand prix from pole after dominating qualifying but Binder was the star of the sprint having started from a lowly 15th on the grid.
The 27-year-old nipped ahead by the second lap after Franco Morbidelli on a Yamaha had been quickest off the start line.
"I surprised myself a little, but what a start," said Binder after finishing 0.072sec ahead of Bezzecchi.
"The plan worked from start to finish."
Morbidelli slipped back to finish fourth with Marquez in fifth.
Maverick Vinales, on an Aprilia, who is second in the championship and was a winner in Argentina with Yamaha in 2017, Jorge Martin, 2021 world champion Fabio Quartararo and Jack Miller rounded out the top 10.
Four riders are missing the Argentina Grand Prix having suffered injuries last weekend in Portugal.
Bagnaia's Ducati teammate Enea Bastianini has a broken shoulder blade.
Spanish veteran Pol Espargaro is facing a lengthy absence due to a bruised lung and fractures to his jaw and spine following a crash in practice.
Six-time premier class champion Marc Marquez is out after undergoing a fifth surgery in less than three years following his spectacular collision with Aprilia rider Miguel Oliveira.
The luckless Oliveira is also sidelined due to a leg injury sustained in that accident, leaving the grid in Argentina reduced to 18 from 22.