Deyverson double gives Atletico Mineiro upper hand over River Plate
Striker Deyverson struck twice and Paulinho added the third as the 2013 champions gave themselves a comfortable cushion ahead of next week's return game at the Estadio Monumental.
"I'm very happy, I hope I can continue like this. We have a game against them now, at their home, with their fans, so we have to be humble," said 33-year-old forward Deyverson.
The striker was a handful all night for the River defence, having thought he had opened the scoring in the eighth minute, but his opportunist finish was ruled out for offside.
But 14 minutes later, the target man with the bleached blond hair struck the first blow -- a long ball from Lyanco was flicked on by Hulk and Deyverson pounced on the loose ball to coolly round Franco Armani before slotting into the empty net.
Four-times Libertadores winners River were struggling to get a foothold in the game, but Facundo Colidio offered a reminder of his quality, cutting in from the right and curling a left-foot shot just wide of the post.
Colombian striker Miguel Borja also went close with a header as the Argentine club, whose stadium will host the final on November 30, showed signs of a revival.
But Deyverson struck again in the 70th minute, his perfectly timed diagonal run allowing him to collect a superb defence-splitting a pass from Guilherme Arana to provide another clinical finish.
The killer blow came four minutes later when River's defense was caught out by a quick-throw to Deyverson, who showed great awareness to slip the ball inside to Paulinho, who fired home, helped by a slight deflection.
River Plate coach Marcelo Gallardo did not hold back in his criticism of the performance.
"I don't think anything came out of what we practiced or tried to develop before the match. When things don't flow, it's difficult to analyze," he said.
"Nothing flowed. Nothing came out of what we had thought. We were a team that suffered in all areas. When that happens against a high-ranking rival... Well, you pay dearly for it, like we did today," he said.
"Nothing is impossible, but we have to play a perfect match. After the disappointment and anger of this night, we have to focus on what is coming, we clearly have to reflect on the match that we could not play and do the opposite for the return match. There is no other way," he added.
Wednesday's other semi-final sees Brazil's Botafogo host Uruguay's Penarol in Rio.