The 35-year-old, who surprisingly joined from Stoke City to act as back-up to the likes of David De Gea and Joel Pereira, is one of Mourinho’s three summer signings, with Fred and Diogo Dalot also joining.
However, Mourinho wanted five new faces through the door and has already publicly declared his frustration at that not yet happening, with the transfer deadline at 5pm on 9th August.
But despite the public perception of the manager during preseason, Grant has insisted Mourinho is upbeat and enthusiastic working behind the scenes.
"From what we're getting from the inside it [the atmosphere around the camp] has been nothing but positive," the United goalkeeper told Sky Sports News.
"He's come in even after the Liverpool game and spoken very highly of what we have given as a team and as a unit.
"The messages we are getting from the manager are positive ones and that is important for us going forward. His attitude and demeanour around the place is great and that is helpful for us especially when we are under-manned and we are working our hardest.
"We are well aware at this stage of the season you have got to work hard and get the minutes into the legs and that is what we are doing."
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