With the first leg at the Bombonera having ended in a 2-2 draw it came as no surprise that Sunday's clash was a nervy encounter early on, with neither side wanting to cede the advantage to their bitter rival.
However, as the first half went on, the River back four began to look shaky, with Boca eventually profiting just before the break.
The goal came from a River attack, with 'Los Millonarios' unable to take advantage when Esteban Andrada was caught out of position.
They were made to regret their lack of a cutting edge within seconds as Boca sprung an attack. Nahitan Nandez found the perfect through ball for Benedetto, who jinked away from the last defender in the form of Gonzalo Montiel to go one-on-one with Franco Armani.
The 33-year-old kept his cool to side-foot a calm finish beyond the River stopper and into the far corner to send the Boca faithful wild.
December 9, 2018