The Portugal international has featured in just 11 matches under new United boss David Moyes this season, despite signing a five-year contract back in September.
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The Portuguese has been widely tipped as one of several players to leave the Red Devils at the end of the season and his agent has done nothing to quash those suggestions.
"Nani is a very important player and at this time the only thing I can say is that he is likely to leave Manchester," Andrea Pastorello told Violanews.com.
Pastorello was speaking to a Fiorentina fan website following reports linking the winger to the Serie A club, which is believed to be leading the race for the Portuguese.
Brazilian midfielder Anderson, who moved to Old Trafford at the same time as Nani in 2008, is currently on loan in Florence and Pastorello says any future talks between the clubs could involve both players.
“The problem for Fiorentina and other Italian clubs is the player’s salary," he added. "But we will evaluate all bids.
“Our relationship with United is great. Fiorentina has to speak with Manchester United about Anderson and maybe there will be an opportunity to talk about Nani, too.”