Why has Lionel Messi not returned to Barcelona from the USA if he's injured?

There has been a lot of excitement generated by Lionel Messi's mini-tour of the United States with Argentina, but he's not been able to generate excitement where he normally likes to: on the pitch.

He did not play against El Salvador and it seems unlikely he will play against Ecuador, either. However, he remains with Gerardo Martino's squad. Why? Even the Argentine media have been wondering why. 

Barça's No.10 has swelling in his right foot, which he suffered in the win over Real Madrid.

Tata has kept him with the group of players he called up, though, as Argentina prepare for this summer's Copa America in Chile. 

Martino wants to press his ideas onto the group, while he also wants to build a good atmosphere. And that is why Messi, who is a big figure in the dressing room, has remained in America. 

National teams have very few chances to get together, so it is important to take advantage of the time they do get. So even if Messi is unable to play against Ecuador, he won't come back to Barcelona early. 

Finally, Argentina are benefitted by keeping Messi with them -- he is the man everyone wants to see and helps them fulfill their financial committments.