As deadline day ticked towards its conclusion there was no sign of an end to the impasse that had United sticking to a maximum 23.5 million GBP transfer fee in line with the escape clause in Fellaini's contract that lapsed at the end of July.
And with Everton chairman Bill Kenwright holding firm on his demand for ?27.5million, the Belgian took matters into his own hands.
Press Association Sport understands that Fellaini offered to waive a ?4m loyalty bonus, which meant United did not have to pay any additional transfer fee and Everton got the overall amount they were demanding.
The move underlines how badly Fellaini wanted to make the switch to Old Trafford, which also included being driven to Everton's Finch Farm training complex on Monday evening to hand in a formal transfer request.
It should at least leave United fans in no doubt where Fellaini's heart lies, even if it was largely a transfer window of frustration for Red Devils supporters.
Club officials have been able to point to the notable achievement of keeping Wayne Rooney, despite Chelsea's clear interest in the England forward.
Wilfried Zaha is also now on board after completing the second half of last season on loan at Crystal Palace and with manager David Moyes seemingly certain to select 18-year-old Belgian Adnan Januzaj in his first-team squad on a regular basis, there is a freshness about United.
Nevertheless, it is a window that will chiefly be remembered for the extended pursuit of Cesc Fabregas that seemed to continue long after it was doomed to almost certain failure.
In addition, United were unable to secure the marquee purchases of Cristiano Ronaldo or Gareth Bale, who are now team-mates at Real Madrid.