United fans were only settling back into work when news broke of Fred's arrival at Carrington on Monday morning.
Fresh from a weekend outing at Anfield, the Brazilian was chauffeured to United’s training ground in the back of a black Mercedes van as the final details were ironed out in the £52m deal.
Just as Alexis Sanchez underwent his medical and promotional duties days before he was unveiled as a United player in January, an official announcement will come at a later date.
And United will not stop there.
Porto defender Diogo Dalot looks set to become the club's second signing of the summer following a breakthrough in talks over the weekend.
United have already agreed on terms with the 19-year-old's representatives and will pay a little bit more than his £17.5m release clause, which becomes active on June 30, to ensure they win the race to sign the right-back.
Totting up United's early business, they will have spent more than £60m in the opening weeks of the summer transfer window. Already, that is 37% of what they splurged in the whole of last summer.
With Mourinho’s unofficial deadline of July 15 in mind, when the players return for pre-season training, United executive vice-chairman Ed Woodward has wasted no time but doing business early and decisively is not always a guarantee of success.
United had four signings secured by July 13 in Louis van Gaal's second summer at the club, back in 2015, but Matteo Darmian, the sole survivor, looks set to be on his way to Juventus this summer.
You can bet that Woodward will make the most of negotiations with Juventus CEO Giuseppe Marotta but, tellingly, there has been no suggestion of including Darmian in any deal for target Alex Sandro.
Both transfers will have to be done separately and Juventus are in a good negotiating position when it comes to hanging onto their left-back.
Kwadwo Asamoah is entering the final weeks of his contract while loanee Leonardo Spinizzola has suffered a serious knee injury.
In other words, they will be keen to keep hold of Sandro unless the player actively pushes to leave or United make a compelling offer.
Given how the Dalot deal caught most people by surprise, the reality is that Mourinho may have another target in mind for left-back.
Having surprisingly made Eric Bailly his first signing as United boss, the same could be said at centre-back.
When it comes to Toby Alderweireld, it is a little difficult to see an obvious resolution in the coming weeks.
The focused Belgian is busy preparing for the World Cup and while Spurs are open to selling him this summer, you can still expect Daniel Levy to drive a hard bargain.
For Woodward, the hard work starts now.