Jorge Sampaoli has admitted Argentina are in an uncomfortable position after a 0-0 draw against Peru left them dangerously close to failing to qualifying for the World Cup.
Should they miss out, it would be the first occasion since 1970 that the two-time World Cup champions, who reached the final against Germany three years ago, will not play in the tournament.
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."
Sampaoli praised Messi for playing with "great intensity", creating opportunities and putting balls "in places that were impossible".
"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".
Now two places outside the qualification zone in sixth, Argentina must beat eighth place Ecuador on Wednesday and hope Peru draw or lose against fourth place Colombia in order to secure a playoff position against New Zealand.