The message could hardly have been more explicit: get transfer business done early. And United's rivals are trying to do the same, with Manchester City having already spent almost £80 million and Liverpool's attempt to get ahead in the race for Southampton's Virgil van Dijk landing them with an official complaint from the Saints.

Late deals a false economy

Last season's double Footballer of the Year, N'Golo Kante, joined Chelsea from Leicester on Jul. 16 the week after France had lost in Euro 2016's final. Meanwhile, Manchester United could not get an £89.3m deal done for Paul Pogba until three weeks later, just five days before the Premier League season started.

Kante was in his stride within weeks, while Pogba took far longer to look comfortable within Mourinho's team, which rather dimmed the star quality he had been bought to add. Pogba eventually came good in the season, though still far short of the same impact as his French colleague. Meanwhile, another Frenchman, Moussa Sissoko, signed by Tottenham for £30m from Newcastle in the closing hours of Deadline Day, showed the misplaced wisdom of spending big late on.

Sissoko never played well enough to win the favour of manager Mauricio Pochettino. A glance at the rest of the deals done on Aug. 31, 2016 brings a picture of unsatisfactory additions, the likes of Islam Slimani, who cost Leicester £30m, and Alvaro Arbeloa, signed as a free agent by West Ham and swiftly dropped.

Only David Luiz, re-signed from PSG by Chelsea, of those final-day deals was a true success, but that was surely helped by his familiarity with a club he had spent three years at from 2011 to 2014.

Players usually need time to acclimatise

Beyond June's two-week Confederations Cup, which will pull players away from Germany, Portugal and Chile of the major football nations, this is a summer without a major international tournament, and will give managers far longer to bed in their coaching philosophy.

For someone like Pep Guardiola, who drills his players to the nth degree, and has plenty of ground to make up on last season, it represents a golden chance to work with almost his entire squad right from beginning of preseason training camp. That is a leading reason for City --still quickly in the hunt for full-backs -- having already bought Bernardo Silva from Monaco, and all but tying up the signature of Benfica goalkeeper Ederson Moraes.

Ederson will replace Claudio Bravo, a disastrous signing hardly helped along by being a late arrival in Manchester from Barcelona last season. Signed in the last week of the transfer window and given no time to work with the defensive unit in front of him, Bravo never recovered.

Longer the wait, higher the price

Liverpool's move for Van Dijk, subsequently reported to the Premier League for "tapping up" suggested a club in a hurry to get things tied up as quickly as possible, perhaps to avoid a bidding war with richer rivals like City and Chelsea.

A much lower transfer budget is available to Jurgen Klopp, hence the haste to get a deal swiftly done. If Van Dijk went to auction, as Southampton would hope, should they be resigned to losing their player, then Liverpool might be blown out of the water on wages as well as transfer fee, as previously happened with failed moves for Alexis Sanchez, who joined Arsenal in the summer of 2014, and Willian, who instead headed to Chelsea a year previously.

Cut your losses early

Mourinho and Woodward may well be glad their attempts to sign Antoine Griezmann were ruled out as a possibility as early as last week. While club sources have since suggested the Frenchman was no longer the priority signing anyway, at least United have the summer ahead to land the strong, physical centre-forward that Mourinho favours.

In United's recent past, the club has become embroiled in lengthy pursuits of players who never ended up putting on the red shirt, with David Moyes and Woodward's summer of 2013 being dominated by a vain pursuit of Cesc Fabregas, who ended up staying at Barcelona.

Instead, while an eleventh hour bid for future United midfielder Ander Herrera fell flat, Moyes was able to add only Marouane Fellaini in midfield, for £4m more than Everton's £23.5m release clause.

Transfer sagas are distracting

Another reason for managers wanting deals done quickly is that they don't much enjoy having to deliver a running commentary on their club's transfer business while trying to prepare their team for the season, usually while on summer tours in locations the other side of the globe from where the deals are actually being struck.

When United visit California, Utah, Texas and Norway this summer, Mourinho will not wish to be answering questions about the possibility of Alvaro Morata being swapped for David De Gea, for example.

And, as happened to United under Moyes, and at Arsenal and Liverpool in recent years, a transfer summer in which targets are missed can cast a dark shadow over the early season.