That football stands above politics in Argentina was rarely in doubt but has been proved once more with interest in Saturday's Copa Libertadores final second leg dwarfing that in the G20 conference a week later in Buenos Aires.

But it is no ordinary Copa final. It is the decisive clash between River Plate and Boca Juniors, the arch-rivals in the Argentine capital, concluding their first meeting in the South American showpiece.

All 66,000 tickets for River's Monumental Stadium are sold with some home fans - away supporters are not permitted - paying 4,800 euros (5,400 dollars) a ticket.

The tie is finely balanced after a 2-2 draw in the first leg two weeks ago in a game delayed by a day due to heavy storms.

Away goals don't count so another draw would lead to extra-time and then possibly penalties.

Even with the long-standing ban on visiting fans in place, some 2,100 police will be mobilised for the match. Over 150 people have lost their lives in football related violence in the last 10 years with 53 of them coming since the away fan ban.

But the police will also be responsible for preventing a rush of fans clutching fake tickets trying to access the stadium.

On Thursday, Boca were given an astonishing send-off by their supporters as 50,000 people crammed into the Bombonera Stadium just to watch them train. And it would have been more had stewards not closed the doors.

That is twice the crowd that attended the anti-G20 demo on Monday with ex Argentine president Cristina Kirchner and former Brazil president Dilma Rousseff.

According to the Clarin newspaper, the training crowd was a world record. "This has energized us," said Boca coach Guillermo Barros Schelotto.

However, the remarkable display has had consequences with city authorities temporarily closing the stadium due to more people than the official capacity being allowed in.

Should Boca lift the Copa, president Daniel Angelici told broadcaster TyC Sports he would apply for the suspension to be lifted so fans could celebrate in the ground.

The winners of the Copa Libertadores will enter the Club World Cup next month to test themselves against the best the rest of the world can offer, including European champions Real Madrid.

Few involved on Saturday are likely to be thinking that far ahead though. Boca have won the Copa on six previous occasions, River three times - but never like this.