Chile and Paraguay can secure two more South American places at the 2010 World Cup alongside five-times champions Brazil if they win their qualifiers on Wednesday.
Chile, who last reached the finals in 1998, are away to Brazil, who are depleted due to suspensions and injury after qualifying with a 3-1 victory in Argentina on Saturday.
Paraguay, looking to reach their fourth successive finals, are at home to Argentina, who have lost their way under Diego Maradona, picking up six points out of a possible 15.
Kaka, one of four suspended Brazil players, was quoted in the Argentine media as saying thrice world champions Argentina must qualify.
"A World Cup without Argentina is not good," he said. "The World Cup needs to have all the best teams in the world."
If Chile and Paraguay win, they will go through to the finals in South Africa, leaving five other teams including Argentina fighting for one more automatic place and a playoff berth in the 10-nation South American group.
Even a draw for Chile and Paraguay would be enough if Colombia and Ecuador, both seven points behind them, do not win on Wednesday.
Paraguay defender Julio Cesar Caceres, who plays for Boca Juniors in Argentina, is back from suspension for the match at the Defensores del Chaco stadium.
"Against teams that have players like Argentina's you must be prepared to pressure them and not let them think," Paraguay's Argentine coach Gerardo Martino told a news conference on Monday.
With three games to go, Brazil lead with 30 points, Chile and Paraguay have 27 and Argentina 22 in the top four automatic qualifying berths.
Colombia, who have missed out on the last two World Cups, have 20 points in fifth, the place that qualifies for a two-leg playoff against the fourth-placed team in the CONCACAF region.
The Colombians visit Uruguay, whose 1-0 defeat away to bottom team Peru at the weekend dented their hopes of at least reaching the playoff.
The good news for Uruguay coach Oscar Washington Tabarez is that striker Diego Forlan, who has scored six goals in 10 qualifiers, is back from suspension. But defenders Diego Godin and captain Diego Lugano are suspended.
Colombia will be without midfielder Fabian Vargas, who injured his left ankle during their 2-0 home win over Ecuador.
The Ecuadoreans, bidding for a third finals in a row, are also on 20 points and away to one-from-bottom Bolivia. They have called up forward Edmund Zura of El Nacional after Carlos Tenorio was injured.
Their forward Pablo Palacios, sent off on Saturday, and defender Neicer Reasco are suspended.
Venezuela, who held Chile 2-2 in Santiago on Saturday, entertain Peru who in June had lost all hopes of qualifying but showed they still have some fight in them with their second win at the weekend.