Argentine world No. 70 Federico Delbonis defeated Germany's Florian Mayer 7-6 (7-4), 6-4 in the first round of the Argentina Open in Buenos Aires.
Delbonis, who needed an hour and 36 minutes to knock off the German at the Buenos Aires Lawn Tennis Club, will play the winner of Tuesday's match between Portugal's Gastao Elias and Spain's Roberto Carballes Baena, who won the title in Quito.
Brazil's Thomaz Bellucci defeated Argentina's Pedro Cachin 6-2, 6-1 in 59 minutes.
Bellucci will play the winner of the match between Argentina's Diego Schwartzman and Austria's Haider Maurer.
In other action on Monday, Serbia's Dusan Lajovic beat Argentina's Facundo Bagnis 7-6 (7-4), 6-1, while Spain's Guillermo Garcia Lopez defeated Argentine veteran Carlos Berlocq 6-3, 6-3.
The last match of the day saw Argentina's Guido Pella rally to beat countryman Nicolas Kicker 2-6, 6-4, 6-4.
The Argentina Open, an ATP 250 event, is part of the tour's South American clay-court circuit, which also includes events in Quito, Rio de Janeiro and Sao Paulo.
The Argentina Open offers $568,190 in prize money.