By FOX Sports Staff
UK newspaper the Daily Mail claims United have been monitoring Thiago for the past three years and even had a £15million bid rejected 18 months ago.
However, Barcelona may be tempted to cash in on the player given his father Mazinho's latest comments.
"My son would play a lot more in any other team in the world," he was quoted as saying.
"He's learning a lot playing with great players but Thiago is very ambitious and needs to play.
"No-one knows what might happen in the future. Football changes a lot and anything can happen. If Thiago wants to go to the 2014 World Cup, he needs to play much more.
"Thiago has the quality to succeed at Barca. But he'd play a lot more at another club. He'd get into any other team in the world.
"I don't know if Barca are buying more players in the summer. They already have a lot of players who can play in the middle. Also, [his brother] Rafinha will be part of the first team squad next season."
The 21-year-old signed a new deal with the Catalans two years ago and is understood to have a buyout clause of €30million (£25million).
Thiago made his first-team debut against Mallorca in 2009.