Dane Richards and Andrew Boyens scored for New York, which actually netted all three goals, as River Plate's equalizer came when Ruben Sambueza's cross to the far post was knocked into his own net by Red Bulls' trialist Aklie Edwards.
There were seven yellow cards handed out, including a second yellow that resulted in the dismissal of New York midfielder Juan Pietravallo in the 87th minute when he tackled an opponent from behind.
New York jumped out to a 1-0 lead in the third minute on a centering pass from Khano Smith that Richards re-directed into the net. Gallardo started the play that produced the equalizer in the 33rd minute with a pass to Sambueza, who put in the cross.
New York scored the winning goal in the 73rd minute to up its record on this trip to 2-0-0. Sinisa Ubiparipovic played a corner kick to the back post, where Boyens got his head to it and bounced it off a River defender. Boyens got to the loose ball and banged it high into the net.
Red Bulls coach Juan Carlos Osorio used two completely different lineups in the first and second halves and sat out Angel as part of a plan to rest the Colombian striker as much as possible during preseason. Angel played the first half and scored the second Red Bulls' goal Tuesday as they beat Velez Sarsfield, 2-1, in Buenos Aires to kick off their schedule in Argentina. New York took an early lead in that game, too, getting on the board with an own goal in the third minute. Osorio changed the team completely at halftime against Velez as well.
"I wanted a good performance and good result," said Osorio following the Tuesday match. "But I think the performance in both halves were good. The effort was absolutely outstanding. It was very hot. Our players are not used to that. But in the end, we won, deservedly. I am pleased. Everybody looked quite good today."
The Red Bulls, 3-1-2 in the 2009 preseason, play Argentinos Juniors on Tuesday. They return from Argentina March 8.
Feb. 26 in Pilar, Argentina
River Plate 1, New York 2. Own goal (Aklie Edwards) 33; Richards 3, Boyens 73.
River Plate - Vega, Musacchio, Pezzella, Quiroga (Diaz 46), Archubi, Gallardo, Domingo, Galmarini (Losanno 46), Fernandez, Sambueza, Rios.
New York (first half) -- Cepero, Edwards, Goldthwaite, Mendes, Hall, Smith, Celades, Rojas, Sassano, Richards, Wolyniec.
New York (second half) - Conway, Traynor, Petke, Boyens, Leitch, Pietravallo, Ubiparipovic, Zimmerman, Borman, Mbuta, Oduro.