File Photo: Barcelona striker Robert Lewandowski (right) fights for the ball with Juventus defender Gleison Bremer. AP
"A significant part of the blaugrana squad has a viral gastroenteritis," Barcelona said in a statement.
The game at the 68,500 capacity Levi's Stadium home of the San Francisco 49ers is part of the Soccer Champions Tour, featuring six top European clubs, and had been expected to draw a large crowd.
Barcelona are scheduled to play against Premier League club Arsenal on Wednesday in Los Angeles before their clash with Spanish rivals Real Madrid in Dallas next Saturday.
Barca finish up their tour with a game against AC Milan in Las Vegas on August 1.
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