Substitute Lucas Barrios netted a dramatic 90th-minute equaliser to earn Paraguay a 2-2 draw against Argentina in their Copa America Group B opener in La Serena.
Barrios - a replacement for Roque Santa Cruz with 11 minutes remaining - fired low past Argentina goalkeeper Sergio Romero after Paulo da Silva had knocked the ball down to his path following a set-piece.
Argentina thought they had the match won thanks to Lionel Messi, who returned to national team duty after helping Barcelona win the UEFA Champions League as part of a historic treble last week and had a hand in both his side's goals at Estadio La Portada de La Serena on Saturday.
The Argentina captain forced Paraguay defender Miguel Samudio into a mistake as Sergio Aguero gave Argentina a 29th-minute lead.
Messi then converted a penalty seven minutes later to put Argentina in control before half-time.
Nelson Valdez pulled a goal back for Paraguay via a stunning long-range strike on the hour mark, and Ramon Diaz's men completed the comeback in the final minute of normal time thanks to Barrios' late intervention.
After a cagey start, Messi almost gave Argentina an 18th-minute lead but his side-footed effort went wide of the post, while a last-ditch Pablo Aguilar tackle denied Aguero four minutes later.
Argentina, though, did not have to wait long for their opener thanks to Aguero - fresh from his first international hat-trick in the final warm-up clash against Bolivia last time out.
Aguero pounced on a misplaced pass from Samudio - harassed by Messi - and rounded goalkeeper Antony Silva with ease.
Messi made it 2-0 for Argentina from the spot in the 36th minute after Angel di Maria had been bundled over by Samudio in the area.
The second half was a much more open affair, with opportunities at both ends.
Messi and his team-mates were a constant threat, but Valdez reduced the deficit against the run of play after an hour.
The Paraguay attacker unleashed a powerful strike into the top corner of the net from outside the penalty area, leaving Romero helpless.
That sparked Argentina into action, Messi and Javier Pastore both presented with opportunities to extend the lead, however both chances went begging.
And with time running out Argentina were made to pay for those missed opportunities, when Barrios rifled the ball into the net from close range to snatch an unlikely point for his side.
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