Messi remained quite healthy last season making 50 appearances for the club, but he has had muscle problems in the past, most notably suffering a string of tears in 2012 and 2013 that has seen Barcelona take a cautious approach with its superstar ever since.
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According to the team, Messi injured his calf in the first training session on Monday, and will not travel with the United States.
The Argentinian striker had to stop and receive treatment from the club doctors in a training session which has affected Valverde's plans for the whole week. Leo Messi will not go to the USA. A while ago, Barcelona shared a video of his arrival at the Camp Nou.
Having been given extended leave following Argentina's run to the semi-finals at this summer's Copa America, Messi only returned to the fold on Monday.
"We'll see each other soon and I send a hug to all". The club did not say when it expects him to be fit again. I back these players and the coaching staff we have. Together, we are going to fight for everything.
SSC Napoli has won two league titles, five Coppa Italias, two Supercoppa Italiana titles, and one UEFA Cup. We do not give it the value it deserves but over the years we will see how hard it was.
Barcelona plays on Thursday at Miami Gardens, Florida, and on Saturday at Ann Arbor, Michigan.
The Spanish champions are also holding a number of fan events while in the U.S.as they look to get closer to their American supporters - a market of particular interest to president Josep Maria Bartomeu.