It didn’t take Lionel Messi long to get on the Copa América scoresheet. It didn’t take much longer for Paraguay to throw Group B into a tizzy.

Tournament co-favorites Argentina watched a first-half lead evaporate as Lucas Barrios scored a last-gasp equalizer to earn Paraguay a 2-2 draw on Saturday in La Serena, Chile, Yahoo Sports report.

The result suddenly leaves Argentina two points behind Uruguay in the group, which was unexpected to say the least.

Boasting arguably the strongest and deepest attacks in the world, Argentina gave Paraguay fits throughout the first half and built a 2-0 lead thanks to a pair of mistakes from Paraguayan defender Miguel Samudio.

A few minutes later, Samudio was judged to have brought down Ángel Di María in the penalty box, and Messi converted the ensuing spot-kick.

Argentina generated several more scoring chances, but Paraguay drew level in the 90th minute.

That Barrios scored such a crucial goal has to sting La Albiceleste. Current Argentina manager Gerardo Martino convinced the Argentine-born Barrios to declare for Paraguay in the run-up to the 2010 World Cup despite holding dual citizenship.

Martino also opted to go for an insurance goal with a 2-1 lead in the second half, rather than fortifying his defense. The introduction of Gonzalo Higuain and Carlos Tevez proved fruitless, and Paraguay pounced.

Saturday’s setback adds major weight to Argentina’s next game, a Tuesday meeting with defending Copa América champions Uruguay. Star striker Luis Suarez is still serving an international ban for biting Italy’s Giorgio Chiellini at the World Cup last summer, but Oscar Tabarez’s Uruguayan side is still a formidable mix of youth and talent.

Simply put, Messi and Argentina will have to be better than they were against Paraguay, or one of soccer’s true heavyweights will be in serious trouble.