Barcelona confirmed to The Associated Press on Wednesday that the Argentine forward's failure to play in Germany on Tuesday will cost the club 30 percent of its fee for the game, a loss of about 360,000 euros ($436,000).
Barcelona beat Hamburg 2-1 on goals by Dani Alves and Gerard Deulofeu. The team was also without its Spanish national team players, still on vacation after winning the European Championship final in Ukraine on July 1.
Barcelona said Messi's response to treatment will determine how long he is out.
The Spanish club plays Moroccan team Raja in an exhibition on Saturday.
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