Xhaka sustained an injury to his left knee in a challenge while training in heavy rain with his international team-mates in Lugano on Thursday, the Swiss Football Federation said.
But an MRI scan that evening showed he had suffered only a bruise to the bone.
"I'm very relieved," Xhaka said on the Swiss FA website.
He will miss Sunday's friendly with Spain, but is not a doubt for the World Cup.
He could be back for Switzerland's second warm-up match against Japan, with their World Cup campaign starting against five-time champions Brazil on June 17.
The 25-year-old has struggled to win over the Arsenal fans since his move from Borussia Monchengladbach in 2016, but is an integral member of the Switzerland side.
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