Gallardo's side drew 2-2 with Boca Juniors in the first leg, but the return match between the Buenos Aires clubs was twice postponed after River fans attacked the Boca team bus.

River have opposed the switch to Real Madrid's Bernabeu, where the match is due to be played on Sunday.

Gallardo called it a "total disgrace".

The attack before the scheduled second leg at River's Monumental stadium on 24 November left a number of players reportedly suffering from dizziness and vomiting, and requiring treatment from club doctors.

"We have lost home advantage," said Gallardo, after his side beat Gimnasia La Plata 3-1 in a league match on Monday.

"Some day we are going to rethink what happened and we will remember it as a total disgrace.

"Our preparations have changed. We are going to play 10,000 kilometres away. The Copa Libertadores of America. They've robbed the fans."

Each team will get 25,000 tickets for Sunday's match, but only 5,000 of them can be sold to fans inside Argentina.

This is designed to prevent the infamous barra bravas, the often violent organised fan groups, from travelling to watch the game in Spain.

The Argentine government said on Monday it was working closely with its Spanish counterparts to neuter the barra bravas and ensure travelling fans would be kept apart in Madrid.