Argentina can all but secure their place at the 2014 World Cup finals in neighbouring Brazil with a win in Friday night's qualifier against Colombia at River Plate's Monumental Stadium in Buenos Aires.
However, Argentina coach Alejandro Sabella was still waiting on the eve of the game to see whether Lionel Messi would be fit enough to take his place in the starting line-up.
The Barcelona star hardly featured for his club towards the end of the season because of a hamstring injury, and while he was named in the squad for this month's qualifying double-header against the Colombians and Ecuador, a decision was only due to be taken on his fitness in Thursday's training session.
"His leg is OK. He looks quick and capable of taking on defenders, but we need to see how fit he is after so long without playing," Sabella said of Messi, who has played in his country's last 32 matches.
Messi's importance to Argentina is obvious, with Celta Vigo midfielder Augusto Fernandez saying: "He can make the difference with one leg, that's why we want him to play."
If Messi does not start, Roma's Erik Lamela and Walter Montillo of Brazilian club Santos are both potential replacements, but there is still a fearsome amount of quality available to Sabella, with Sergio Aguero and Gonzalo Higuain likely to start in attack.
Group leaders Argentina are four points clear of Ecuador and five ahead of third-placed Colombia, whose attack will be led by Radamel Falcao, the former River Plate striker.
Coached by Jose Pekerman, the Argentine who took his native country to the 2006 World Cup, Colombia are looking to qualify for the finals for the first time since France '98.
"We are not scared of Argentina. Our players are all performing well for their clubs just now and that gives us confidence," said Inter Milan midfielder Freddy Guarin.
"The qualifiers are not easy, but we are at a level where we are capable of competing against anybody on the international stage."
Since losing 4-0 to Argentina a year ago, Ecuador have won four and drawn two of their last six qualifiers to close in on a return to the finals after missing out on South Africa in 2010.
They go to Lima to face a Peru side who desperately need a win to revive their qualification hopes, and Reinaldo Rueda's visiting side are likely to be able to call on the services of Lokomotiv Moscow dangerman Felipe Caicedo for the game.
Later on Friday night, Chile, who currently occupy the fourth and final automatic qualifying berth, travel to Asuncion to face struggling Paraguay.
Paraguay have reached the knockout stages of the last four World Cups and were beaten finalists in the 2011 Copa America, but they are bottom of the group with just eight points from 11 qualifiers so must take advantage of the fact that four of their last five matches are at home.
"We are still alive and will fight to the very end," said Paraguay's Uruguayan coach Gerardo Pelusso.
Chile have been inconsistent in this qualifying campaign but beat Uruguay 2-0 in their last outing in March to sit level on points with Venezuela, who remain in contention to qualify for the finals for the first time.
However, they must negotiate a treacherous visit to the high altitude of La Paz for Friday's game against Bolivia.
The thin air of the Bolivian capital - situated almost 12,000 feet above sea level - forced Messi to vomit on the pitch when Argentina drew 1-1 there in a qualifier in March.