CONMEBOL president Alejandro Dominguez called for fans to behave in Madrid after the Copa Libertadores final second leg was rearranged.
Boca Juniors and River Plate will meet at the Santiago Bernabeu on December 9 to complete a tie which is locked at 2-2.
The second leg, which was due to be played at River's El Monumental, was postponed after the Boca bus was attacked on its way to the stadium.
Dominguez again criticised the fans' actions but is eager for supporters to enjoy the second leg in Spain.
"The decision of the administration is that the match is played with supporters of both clubs in the city of Madrid, at the Bernabeu Stadium," Dominguez told a news conference. "It will be Sunday December 9 at 20:30 CET.
Final de la CONMEBOL Libertadores 2018 se jugará el domingo 9 de diciembre en el Santiago Bernabéu de Madrid.November 29, 2018
"Spain is the country with the largest Argentine population outside of its country. Madrid is one of the 10 safest cities in the world and it has a great football culture. I want everyone who goes to show how to enjoy and have a good time.
"I sympathise with the players who were injured, and I want to repudiate what has happened. The ball is never going to be stained by unscrupulous people, it will keep rolling."
Boca are appealing CONMEBOL's decision not to award them the title after the attack.
