The Daily Mail says United's eleventh hour attempt to sign Coentrao on loan from Real Madrid reportedly collapsed because the paperwork could not be completed on time.
Reds boss David Moyes hoped to sign the Portugal defender on a season-long loan after failing to land Everton left back Leighton Baines.
But, whilst the initial paperwork was sent to the Premier League on time, and La Liga issued a statement confirming the deal, it is understood Real opted not to complete the final part of the transfer after the player lined up to replace Coentrao, Granada full-back Guilherme Siqueira, ended up at Benfica instead. La Liga officials later retracted the statement.
It meant FIFA were unable to confirm the loan and Coentrao will remain in the Spanish capital.
For the big stories and the banter follow us on Twitter: @tribalfootball