Hundreds of Boca Juniors fans gathered outside their team's hotel in Madrid on Saturday, chanting "It doesn't matter where you play, we will always follow you".
The Buenos Aires city rivals will now play their twice-delayed second-leg game Sunday in Madrid.
The tie was first postponed last month after River fans attacked the Boca team bus as it travelled to the game.
The first leg, played in Buenos Aires, ended in a 2-2 draw.
Officials said almost 4,000 security personnel will be deployed for Sunday's match, nearly double the number used in the "clasicos" between Real Madrid and Barcelona.
For hardened Argentine soccer fans already wrestling with a weak currency and some of whom spent a small fortune cheering on the national team at this year's World Cup in Russian Federation, it's a pre-Christmas excursion they could do without. River or Boca, however, would enter the competition with a semi-final on December 18.
Fans of both clubs are beginning to arrive in Madrid amid calls for calm.
The game was postponed in part due to injuries suffered by the Boca players, with some suffering cuts from broken windows, and Tevez was himself pictured struggling to breathe after exposure to tear gas.
For each club, the 20,000 tickets allocated to fans in Spain and elsewhere sold out within hours but some of the 5,000 for residents in Argentina remain available.
Two fan zones will be set up on either side of the stadium.
A similarly applaudable Lucas Pratto goal levelled things after the interval to secure an extra 30 minutes, and Wilmar Barrios' sending off handed River the initiative, as Quintero gloriously put them ahead and then Martinez rounded things off in the closing stages.
Title celebrations would take part in different areas of the city. Nahitan Nandez's superb pass split two River defenders and Benedetto kept a cool head, guiding into the corner, before taunting the beaten Gonzalo Montiel.
The victor of the Copa Libertadores will represent South America in the coming Club World Cup which begins December 12 in the United Arab Emirates.