READ MORE: Boca Juniors & River Plate fans take over Madrid ahead of Copa Libertadores final (PHOTOS/VIDEO)

A Juan Manuel Martínez goal at the death and a  smart finish  from Juan Fernando Quintero clinched the game in extra time, after Lucas Pratto canceled out a Dario Benedetto opener for Boca in a high-temp game that had been postponed after River fans ambushed the Boca team bus ahead of 'the biggest derby in world football', forcing the game to eventually be rescheduled for December 9 in the Spanish capital.

After possibly the most drawn-out build up to a match in recent history - the first leg of the  'biggest derby in world football’ took place almost one month ago at Boca’s La Bombonera home in Buenos Aires, ending 2-2 - a first-half goal from Dario Benedetto was leveled by Prato in the second half, before goals in extra time from Quintero and then Martinez into an open net as Boca searched for a goal with every player inside the River area.

The original date was scheduled to take place on November 24, but River fans ambushed the Boca team bus as it headed to River’s El Monumental stadium, injuring the team’s players and forcing it to be postponed by 24 hours. The rescheduled date was again postponed amid a complaint from Boca, who even demanded they be crowned champions without a final match.

After a meeting in Asuncion, Paraguay, the South American football federation CONMEBOL decided to move the fixture to Spain on grounds of “equality” and to avoid any repeat of the ugly scenes that postponed the original tie, forcing many fans to watch the match from afar, with those not traveling to Spain crowding around TVs on the streets of the Argentine capital.

A host of Argentine footballing royalty attended the match, including Paulo Dybala, the already legendary Lionel Messi and former La Albiceleste captain Javier Zanetti, both River and Boca fans flooded the Spanish capital.