Fernando Gaviria (Colombia) took a dramatic victory on Stage 1 of the Tour de San Luis.
The 20-year-old out-sprinted Mark Cavendish (Etixx-QuickStep) and Sacha Modolo (Lampre-Merida), who finished second and third respectively.
The day's breakaway was formed of just three riders: Leandro Messineo (San Luis Somos Todos), David Williams (Jamis-Hagens Berman), and Ignacio Pérez (Team San Juan).
The built up a lead of more than four minutes at one point, but as the sprinters' teams, and Etixx-QuickStep in particular, began to take control at the front of the peloton, the gap began to fall.
The trio were eventually reeled in with 15 kilometres to go.
Several riders tried their luck with a number of counter-attacks inside the closing kilometres, but none could stick and the stage came down to a bunch sprint.
World champion Michal Kwiatkowski got the Etixx-QuickStep lead-out underway, but Cavendish was unable to capitalise as Gaviria, who held on to take the win in Villa Mercedes.
"I was really nervous before the start because I had some great riders next to me," said Gaviria, a former junior world champion on the track.
"But when you beat such big riders in a sprint, it makes it a more important victory."
The Tour de San Luis continues on Tuesday with the peloton covering 185.3 kilometres between La Punta and Mirador de Potrero.