Reports in Italy suggest that Vidal is set to undergo a medical at the Red Devils on Thursday ahead of a big-money move to the 20-time English champions.
Vidal is one of our players, we renewed the contract last season
The 27-year-old midfielder has been linked with a switch to Arsenal and Liverpool, too, although United appear to have on the race to sign the Chilean.
However, Juventus general director Marotta reiterated that Vidal is set to stay at the Serie A champions despite talk of a move to Old Trafford.
“Vidal is one of our players, we renewed the contract last season,” Marotta told Sky Sport Italia.
“We are happy with him, he is pleased with us, he is wearing the shirt of the most prestigious club in the world. I do not think there will be any problems.”
Vidal, who scored 11 top-flight goals last season, has won three successive Serie A titles since moving to Turin from Bayer Leverkusen in 2011.
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