With just three points separating Costa Rica (12 points) from the fourth placed Mexicans (nine), the two rounds of qualifiers on Saturday and next Wednesday will go a long way to deciding which teams from North and Central America and the Caribbean head to the finals in South Africa next year.
The top three teams in the six-nation final qualifying group automatically advance to South Africa while the fourth placed team faces a two-legged playoff against the fifth-placed South American team.
Mexico made a poor start to qualifying under former coach Sven-Goran Eriksson, losing to the United States and Honduras.
El Tri were then beaten by El Salvador in Javier Aguirre's first qualifier in charge but their recent victory over the U.S in Mexico City has put them back in contention.
The third-placed Americans (10) will expect to pick up maximum points from their games - at home to fifth-placed El Salvador (five) on Saturday and away to bottom team Trinidad and Tobago (five) on Wednesday.
The artificial surface in Costa Rica is one of the major worries for Mexico according to striker Miguel Sabah - whose late goal at the Azteca stadium secured a 2-1 win over the U.S last month.
"We know that the field is horrible, so playing good football will be difficult. We might have to do different things to try and win the game but the most important things will be concentration and order," he said.
Mexico's chances have been hampered by the loss of injured Barcelona defender Rafael Marquez and Arsenal forward Carlos Vela.
The Mexicans are at home to second-placed Honduras (10) on Wednesday while Costa Rica travel to El Salvador.
Honduras, featuring in-form Tottenham midfielder Wilson Palacios, have been the surprise package so far and face Trinidad on Saturday before the crunch game at the Azteca.
Inter Milan forward David Suazo will return to the Honduran attack on Saturday in place of the suspended Carlos Costly.
