The fan, who was wearing Messi's Barcelona jersey, ruffled Messi's hair a bit before surrendering to security and allowed himself to be taken away. Messi was left to wipe himself down with his shirt before finishing out the match, which Argentina won 3-2.
Messi has shown to be friendly to pitch invaders wishing to meet him up close. However, this may not be the best approach for Messi to use going forward, as it may encourage more people to do this, and you never know what stunt a fan might pull the next time. Of course, it wouldn't hurt for these stadiums to increase security when Messi comes to town.
DISCLAIMER: Holdout Sports does not condone this type of behavior.
H/T Dirty Tackle.