Mourinho brought Willian to England from Shakhtar Donetsk five years ago and the Red Devils have been touted as a possible destination for the attacker recently following his lack of playing time for the Blues.
The FA Cup victor was in action for the Selecao in their 1-1 draw with Switzerland's on Sunday evening, but played 20 games for the Blues' in their Premier League campaign last term.
And the bookies have cut the odds on Willian joining United with Mourinho tipped to splash the cash in the coming weeks.
According to the Daily Mail, United are ready to lodge a €60 million bid for the Brazilian worldwide. I hope he does well at Manchester United.
Newcastle's current transfer record is £16 million, in a deal dating back to 2005, when the club landed Michael Owen from Real Madrid under the tenure of Graeme Souness. "He has a lot of qualities", the Chelsea player was quoted as saying before jetting off for the Mundial.
Willian is a part of the Brazil side taking part in the World Cup and also took part in the 1-1 draw against Switzerland, their World Cup opener.
"He can improve (them) a lot".
"Hi Gunners, it's Granit, I'm happy and proud to sign a new contract here for Arsenal", Xhaka said in a video message posted on social media.
Rafa Benitez is preparing for a vital summer of recruitment after managing to secure a top-half finish in the Premier League table. "We talked a little bit about that".