Lionel Messi vomiting during matches for both Argentina and Barcelona has gained a lot of notice this season because it keeps happening and no one knows why. Messi himself has written it off just as a thing that happens during matches, at training and even when he's at home, but his manager at Barcelona this past season said, "Something is not right."

He was filmed dry heaving during Argentina's most recent friendly against Slovenia and now national team manager Alejandro Sabella has weighed in with a theory of his own. From the AP:

“Nerves. I reckon that in these moments there is anxiety more than anything,” Sabella said before the team departed for Brazil, where they open their World Cup campaign against Bosnia-Herzegovina on Sunday. “It’s difficult to remain calm.”
Granted, Messi does have an incredible amount of pressure on him as an Argentine public that never quite warmed to him expects him to play for them the way he does for Barcelona and deliver a World Cup title like Maradona did. The vomiting doesn't seem to impact his performance, though. As far back as 2011, he's proven he can puke and rally by following his regurgitations with goals.

Whether it's nerves or just a side effect of being one of the world's greatest footballers, it seems likely that Messi will heave at some point during the World Cup. But if he ends up lifting the trophy at the end, Brazilians will be doing the same.