Two-time World Cup champions, Argentina are in danger of missing a first World Cup since 1970 after being held to a goalless draw by Peru.
The La Albiceleste (The White and Sky Blue) have reached three major finals in three years but the team who came so close to winning the 2014 World Cup face a crunch game against Ecuador.
They must now win their final qualifier in Ecuador to claim at least fifth spot which sets up a two-leg play-off against New Zealand.
Only the top four in South American qualifying are guaranteed a place at the 2018 tournament in Russia, and Argentina are sixth with one game left.
The final round of games kick-off at 00:30 BST on Wednesday, 11 October.
Argentina are level on both points (25) and goal difference (+1) with fifth-placed Peru, who are ahead on goals scored.
So tight is the group that four points separate Uruguay in second (28) and Paraguay (24) in seventh and a win for Argentina could see them qualify automatically.
However, they have drawn their past three qualifiers and their recent record in Ecuadorian capital Quito, which is 2,900m above sea level, is poor, losing two out of their past three and drawing the other.
Ecuador have lost their previous five qualifying games.
Peru are hosting fourth-placed Colombia and should they draw, Argentina would be eliminated if they did not win.
Chile, who are third, go to already-qualified Brazil, while Uruguay, who are all-but assured of their place in Russia because of their vastly superior goal difference, need just a draw at home to already-eliminated Bolivia to guarantee qualification.
Jorge Sampaoli keeps the faith despite goalless draw with Peru
Speaking after the disappointing result Sampaoli said there remained an ‘atmosphere of enthusiasm’ within the squad that they could still qualify.
‘I am very confident that if we play with the conviction with which we did it today we will be in the World Cup,’ he said.
‘Today Argentina was far superior to Peru, playing with a lot of authority.
‘The situation is not comfortable. But the ranking still depends on us.
”We could not beat them on the scoreboard but they did in the game. We are very hopeful for everything that comes.’
Lionel Messi hit the post in the second half and Sampaoli praised the Barcelona forward’s “great intensity” as he created numerous opportunities that his team-mates were unable to convert in front of a 49,000-capacity crowd at La Bombonera in Buenos Aries.
‘I am convinced that if we are as we were today, that Argentina is going to the World Cup,’ he said.
To add to Argentina’s woes, Boca Juniors midfielder Fernando Gago suffered a serious injury, tearing his anterior cruciate ligament and internal lateral ligament in his right knee.
Sampaoli said losing the midfielder as a ‘blow’ as he was a ‘very valuable player’.
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