Reports suggested the Juventus star, 27, had hurt the knee on which he underwent surgery before the World Cup in Brazil.
But, speaking ahead of his side's clash against Mexico on Saturday, Sampaoli said that was not the case.
Just hours after Vidal had tweeted that his knee was "perfect", Sampaoli said likewise at his pre-match news conference.
"If Vidal wasn't in a condition to play, Juventus wouldn't have given him to us," the coach said on Friday.
"Today his knee is perfect."
Sampaoli confirmed Vidal would leave the camp after the Mexico clash to return to Italy, meaning he will miss the Haiti encounter on Tuesday.
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