Mourinho had asked the club management to sign a defender after most of his defenders picked up injuries during their pre-season tour and Jerome Boateng who Bayern Munich was ready to listen to any offer for, became United's target.
A number of other centre-backs were tracked but the club found few realistic options to markedly improve their backline as they attempted to balance long-term success with Mourinho's hunger for silverware.
Jean Michael Seri was a transfer target for Barcelona just 12 months ago, but will now be lining up at Craven Cottage rather than the Camp Nou along with former Nice team-mate Maxime Le Marchand, German World Cup victor Andre Schurrle and Alfie Mawson, who earned an England call-up earlier in the year.
Manchester City bolstered their attacking line with the club record signing of Riyad Mahrez but were not as active in the transfer window as they were this time previous year.
Despite slashing a club record £60 million on signing Riyad Mahrez, City have enjoyed a quiet window.
Mauricio Pochettino backs Tottenham to improve despite lack of signings
Paul Merson is backing Tottenham Hotspur to finish in fourth place ahead of Arsenal in the Premier League table this season. Tottenham failed to make a single signing this summer, in a transfer window which frustrated many of their supporters.
Nearly every top-flight club strengthened their squad either on deadline day or in the weeks before, the clear exception being Tottenham Hotspur who set a record for being the first top-flight English club since the summer window was introduced in 2003 not to bring in a single new name to bolster the squad.
Australian teenager Daniel Arzani joined the English champions from sister club Melbourne City on Thursday but is expected to be sent on loan to Celtic.
"It's not about adding because it's fashionable to sign players", Tottenham manager Mauricio Pochettino said on Thursday. "We must get used to teams who have players of the same quality that we have".
Wolves could also build on an impressive summer of dealing on their return to the top flight with a deal for Belgian global Leander Dendoncker from Anderlecht.
Fulham announced five players, all after the deadline - Marseille midfielder Andre-Frank Anguissa in a £22.3m deal, Bristol City left-back Joe Bryan for £6m and Sergio Rico, Luciano Vietto and Timothy Fosu-Mensah on loan.