Honduras and Costa Rica fight for finals spot
They will need some help, however, from the United States to avoid the play-off route and pip Costa Rica to third place.
The United States and Mexico have secured two of the three automatic spots for the 2010 finals in South Africa, while Costa Rica's 4-0 win over bottom team Trinidad and Tobago has pushed them into third place.
The Costa Ricans have a two-point advantage over Honduras but play the United States in Washington knowing that a defeat could leave them in a play-off against the fifth-placed team in South America - currently Uruguay but possibly Argentina.
Honduras, whose campaign in Spain 27 years ago was its only World Cup appearance, lost 3-2 to the United States in a thriller in San Pedro Sula on Saturday.
They now must pick themselves up and do what no team has managed in the final qualifying stages - win in El Salvador.
"We all want to go to the World Cup. We've got a social and professional responsibility with the fans," Honduras coach Reinaldo Rueda told a news conference in El Salvador.
"I imagine it is going to be a tense game, just like it was in San Pedro Sula ... El Salvador want to finish well for their fans and for the great job they have done."
Rueda will have to decide whether to start with David Suazo in attack or stick with Saturday's pairing of Carlos Costly and Carlos Pavon.
Although eliminated, El Salvador will not lack motivation against their long standing rivals.
"We are professionals and we are going to take the game very seriously and responsibly. We want to finish well," said El Salvador's Mexican coach Carlos de los Cobos.
A win for Costa Rica would secure third place regardless of other results, while a defeat or draw would be damaging if Honduras, who have a better goal difference, win.
"We have a chance to qualify directly and we must try to seize it," said Costa Rica's Brazilian coach Rene Simoes.
"We are not thinking about play-offs or Argentina or things down the road that we can't control. We are just thinking about winning our game."
The United States insist they will be do their utmost to beat Costa Rica and finish top of the group, but have been rocked by the news that striker Charlie Davies was seriously injured in a car crash early on Tuesday morning.
Mexico finish their campaign away to Trinidad and Tobago.