Mourinho warned at the weekend that United would face “a difficult season” if he did not land a new centre-back but, despite being linked to four targets, it is understood United are not close to pushing any of them over the line before today’s 5pm deadline.
That is bound to increase the tension between Mourinho and United’s hierarchy ahead of tomorrow’s Premier League opener against Leicester at Old Trafford.
The Foxes have made it clear they will not sell Harry Maguire – Mourinho’s top target – at any price.
Privately, the England defender is still hoping a deal can be struck because he wants to play Champions League football but he will not rock the boat by asking for a move.
United have dropped their interest in Jerome Boateng because they will not match Bayern Munich’s £45million for a player who is 30 next month.
He has also had a lot of injury problems over the last three years as well as endured an unhappy one-season spell with neighbours Manchester City earlier in his career.
United got their fingers badly burned when they bought injury-prone Bastian Schweinsteiger from Bayern in 2015 when he was clearly past his best. And they are wary of another expensive mistake.
A £35m move for Barcelona’s Yerry Mina has stalled, believed to be over the excessive agents’ fees involved and concerns whether the Colombian is good enough.
And despite some interest in Tottenham’s £50m-rated Toby Alderweireld, United have not tabled a bid for the Belgium international, who is 30 next March and, like Boateng, would have no re-sale value.
United officials are adamant they will not be held to ransom at such a late stage of the transfer window.
And Woodward and his fellow directors do not see the point of panic buying and bringing in players who, in their opinion, are no better than what United already have.
They will also point out that Mourinho has bought a centre-half in each of the last two summers – Eric Bailly for £30m in 2016 and Victor Lindelof for £31m last year – and both have potential to develop.
On top of that United have long-serving duo Chris Smalling, Phil Jones plus Marcos Rojo.
Three of those players – Lindelof, Jones and Rojo – were considered good enough to play in the World Cup for their countries.
United have also made it clear they will not sell Paul Pogba or Anthony Martial but it is the lack of any more incoming players that will annoy Mourinho, who has repeatedly talked in pre-season of “the list” of targets he gave to Woodward towards the end of the season.
He has spent more than £70m on midfielder Fred, right-back Diogo Dalot and back-up goalkeeper Lee Grant but wanted two more players – a winger and a centre-back.