It's happening again.
Local giants Boca Juniors and River Plate will once again clash in the Copa Libertadores, though this time in the semi-finals, after both clubs secured passage to the continental competition's final four this week.
The two Buenos Aires giants are set to write a new chapter of their bitter rivalry and this time Boca will be desperate for revenge after last season's defeat in the final to their arch-rivals.
What happened last time out in Madrid, in Real Madrid's Santiago Bernabéu stadium, remains fresh in the memories of both sets of fans. River secured an 3-1 victory to seal the tie 5-3 on aggregate.
However, most of the headlines were written off the pitch. After a 2-2 draw at La Bombonera in the first leg, hooligan violence and an attack by River fans on Boca's team bus forced the game's cancellation, prompting the CONMEBOL regional governing body to switch the second leg to Madrid.
Now the two sides will go head-to-head – hopefully at their own stadiums – in the final four of this season's edition of the Libertadores.
The Millonario secured their place on Thursday night, after a 1-1 second-leg draw with Cerro Porteño in Asunción.
Veteran striker Nelson Haedo Valdez had put the home side ahead but Uruguayan Nicolás De La Cruz levelled things on 52 minutes for the Millo.
River had bagged a 2-0 win in the first leg.
The Xeneize had qualified for the last four the previous night, eliminating Liga de Quito 3-0 on aggregate (0-3 and 0-0).
As an appetiser for what is sure to be two explosive semi-final clashes, River will host Boca on Sunday in matchday five of the Superliga.
The other semi-final in the Libertadores, meanwhile, will be an Brazilian clash of Grêmio versus Flamengo, so the final of the Libertadores will be contested by a head-to-head between Brazilian and Argentine sides.
The semi-finals are scheduled for October 2 and 3 (first leg) and October 23 and 24 (return), according to CONMEBOL.