Ecuador is one win away from returning to the World Cup after a 1-1 home draw with South American qualifying leaders Brazil.
Coach Gustavo Alfaro’s team will qualify to play in Qatar if it beats Peru next week.
Elsewhere on Thursday, Chile, once a force in the region, saw its chances shrink dramatically after a 2-1 home loss to second-place Argentina who had rested Lionel Messi for the game.
The Chileans will have to pull good results at Bolivia and Brazil, with their last match in the competition likely to be in Santiago against bitter rival Uruguay.
Uruguay, meanwhile, rose back to contention after a 1-0 win at Paraguay, with a goal by veteran Luis Suarez.
It was the team’s first win for new coach Diego Alonso, who took over after veteran Oscar Tabárez was fired due to poor results.
Brazil (36 points) and Argentina (32) have already qualified for the World Cup.
Ecuador has 24 points, five ahead of Uruguay. Colombia and Peru, which will clash in Barranquilla, Colombia, on Friday, are at 17 points.
Chile has 16 and could be overtaken by Bolivia (15), which will travel to Venezuela – the only team in the region out of contention for a spot.
South America has four direct World Cup spots, and the fifth-place team will play an international playoff for a berth.
US, Canada win to lead CONCACAF World Cup race
Canada and the United States stayed on course for World Cup qualification with crucial wins on Thursday as Mexico reignited their campaign with victory over Jamaica.
Canada, looking to qualify for the World Cup for the first time since 1986, scored a disciplined 2-0 away victory over Honduras in San Pedro Sula to stay on top of the CONCACAF standings with 19 points from nine games.
The USA – desperate to qualify for this year’s tournament after their shock failure to reach the 2018 World Cup in Russia – boosted their chances of qualification with a 1-0 win over El Salvador in Columbus, Ohio.
In other games on Thursday, Mexico snapped their two-game losing streak with a battling 2-1 win over Jamaica in Kingston.
Mexico are one point behind the US with 17 points from nine games.
Costa Rica edged Panama 1-0 on a goal from Bryan Ruiz, the defeat leaving Panama three points behind Mexico in the standings and Costa Rica a further two points back.
The top three teams qualify automatically for the finals in Qatar, with the fourth-place team advancing to a playoff.