Shakhtar Donetsk midfielder Fred featured as an 82nd-minute substitute in Brazil's 2-0 friendly win over Croatia at Anfield on Sunday and Globo's sports website said he would then take the short trip to Manchester to undergo a medical prior to a 55 million euro ($47.13 million) transfer.
Asked about the reports, Brazil coach Tite said: "When this happens, and it is inevitable, they are going to come to us and our advice to them is resolve this as soon as you can so your head is back with us and focussing on the national team."
"If I was a manager I'd ask to sign him as well," he added.
The 25-year-old central midfielder joined Ukrainian club Shakhtar from Brazilian side Internacional in 2013 and has been a part of their Champions League campaigns.
United did not immediately respond to a request for a comment.
A spokesman for the Brazilian Football Federation (CBF) declined to comment on the reports but said the team would have a day off on Monday.
Brazil will play another friendly, against Austria in Vienna, on June 10 before heading to Russia where they will face Switzerland, Costa Rica and Serbia in Group E.
(Reporting by Simon Evans, editing by Neil Robinson)
