Daniel Diaz (Funvic) took the win on Stage 2 of the Tour de San Luis with a late attack.
The 25-year-old attacked twice on the final climb, going clear of first the peloton and then his fellow escapees, to claim the win in his home country.
Five riders went clear early in the 185.3 kilometre stage from La Punta to Mirador de Potrero: Mauricio Muller (San Juan), Sebastián Tolosa (Buenos Aires), Lucas Haedo (Jamis-Hagens Berman), Carlos Quintero (Colombia), and Romain Guillemois (Europcar).
At one stage their advantage over the main field stood at more than four minutes, but with 20 kilometres to go they had just over two minutes and had lost a rider, with Tolosa unable to maintain the pace.
Movistar then took control at the front of the peloton, bringing the gap down further, and the break was caught as the riders reached the lower slopes of the final climb.
A group of eight, including Diaz and pre-race favourite Nairo Quintana (Movistar), made a move and were joined by several others midway through the 4.8 kilometre climb.
With more than a kilometre still to race, Diaz made his move, attacking along with Rodolfo Torres (Colombia). And it was the Argentine who had the most left to offer, surging clear of Torres to take a fine solo win.
Torres held on to finish second, while Kleber Da Silva (Funvic) rolled in third.
The win meant that Diaz, who won the overall title at the 2013 Tour de San Luis, took over the lead on GC from sprinter Fernando Gaviria (Colombia), who won Stage 1.
"The pace was really very fast on the climb today with a lot of attacks at the bottom, especially because San Luis Somos Todos were trying to force a selection," said Diaz.
"It was the attack from the Colombian [Torres] that helped to make the final selection and I was able to follow him."