The Daily Mail says Avram Grant had to start from scratch when Mourinho departed at 10am last Thursday with the detailed dossiers and form guides on key United players that had been prepared for him by opposition scout Andre Villas.
Chelsea players, who usually have a clear indication of the team a day in advance of a match, were also left in the dark about the line-up until 2pm yesterday.
Grant did not take the players for training on Saturday because he was observing Yom Kippur and, to the dismay of senior players, he delayed revealing the team until he arrived at their hotel in Manchester.
Mourinho had been due to give the players their individual dossiers after they returned from a day off following the 1-1 draw with Rosenborg on Thursday morning.
That was until Mourinho left the club "by mutual consent" on Wednesday evening.
Chelsea's owner Roman Abramovich gave consent for Mourinho to say goodbye and pick up his personal effects from the club's training ground last Thursday, but probably didn't realise the Portuguese had departed with his scouting reports and other statistical data.