Velez Sarsfield had to work until the last minute to beat Union Espanola 3-2 in the first leg of the Copa Sudamericana.
The Chileans were 2-1 ahead but Velez netted two goals in the final two minutes to claim a crucial win ahead of the second leg in Santiago next week.
Uruguayan striker Hernan Rodrigo Lopez gave Velez the lead in the 23rd minute, but Union Espanola went ahead with a 33rd-minute goal by David Ramirez and a 60th-minute strike by Raul Estevez.
! But an own goal by Diego Resende levelled it up in the 90th minute before Rolando Zarate's header secured the victory.
Velez coach Ricardo Gareca said: "We won the kind of match you usually lose. I am proud of my guys.
"Sometimes you don't get to know the rivals so well. You can watch some videos but things change on the field. Tonight, we played a team who play similarly to us and it was difficult."
In Porto Alegre, the reigning Copa Sudamericana champions Internacional could only draw 1-1 at home to Universidad de Chile.
The visitors went ahead thanks to a long-distance shot by Argentinian midfielder Walter Montillo in the 23rd minute.
Inter only managed to level the game 32 minutes into the second half, when Kleber beat Miguel Pinto after good work by Andres D'Alessandro.
Inter midfielder Andrezinho said: "We started the game very badly, as we took too much time to mark well. When we managed to do that, we dominated.
"We s! till have a return match in Chile. We know it will be tough, b! ut the t eam is used to playing this type of knock-out match."
In Rio de Janeiro, Botafogo defeated Ecuador's Emelec 2-0, with Renato scoring the first goal in first-half injury time.
Eighteen minutes after the interval, Andre Lima headed a Juninho cross.
Brazilian side Fluminense drew their away game against Alianza Atletico of Peru.
Fluminese took an early lead with Luiz Alberto Da Silva scoring at the sixth minute.
Second-half goals by Saulo Aponte and Marcio Valverde put Alianza Atletico ahead before Argentinian playmaker Dario Conca equalised in the 74th minute.
