The England international has enjoyed a sensational season under Dean Smith, though injury has curtailed his impact in recent weeks.
Grealish has been linked with a move to Old Trafford in recent years, but Barnett maintains that Ole Gunnar Solskjaer’s side are one of many clubs interested, with several rivals leading the chase ahead of the Red Devils.
“The truth is we don’t know [what will happen],” Barnett told SNTV.
“There are many clubs [interested] and I wouldn’t put Manchester United at the top of that [list].
“But he could stay. He could stay as well so it’s a conversation the club, Aston Villa, will have with Jack and ourselves then we’ll see where we go.”
The Villa captain, 25, has shone this season, scoring six goals and making 10 others in 22 league appearances.
Barnett recently told Sky Sports that Grealish “loves” Villa and that he can overcome his current injury issues due to his “great mentality”.
“He loves Villa, but I think we just have to wait to see how things pan out,” Barnett said. “At the moment he is a Villa player and he has had no thoughts about anything else.
“We have to do what is best for Jack and for everybody else. I think he is a very special player. I think he maybe should have been playing for England a little earlier.
“It is unfortunate that he has got this injury at the moment but that will be fine. He has got a great mentality.
“On the field, he knows exactly what he wants to do, how to do it. I think he could be a big star in the summer. Only hope that he is given a chance and that will be great.”
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