Jose Angulo scored twice as Independiente del Valle won 2-1 in the opening leg of their Copa Libertadores quarter-final tie, but Pumas UNAM will fancy their chances following Fidel Martinez's late away goal.
Angulo completed his brace with a goal either side of half-time, putting Ecuadorian hosts Independiente in the box seat in Quito on Tuesday.
However, Martinez came off the bench and netted a priceless goal on the road with 17 minutes remaining at the Estadio Olimpico Atahualpa.
Independiente had to wait until the 43rd minute to opening the scoring, Angulo latching on to Junior Sornoza's perfectly-waited through ball over UNAM's defence and chesting it down before scuffing his effort beyond goalkeeper Alejandro Palacios.
Angulo was at it again 10 minutes into the second half when the 21-year-old rose highest in between two defenders and headed past Palacios for his third goal in two Copa Libertadores matches.
Pumas, though, had the final say as Independiente looked set to keep a vital clean sheet.
Second-half substitute Martinez pounced on a rebound on the edge of the six-yard box as he gave the Mexicans hope heading into the return leg on May 24.