First, the relief!
A United statement has confirmed that Wayne Rooney suffered only minor ligament damage to the ankle he injured in the dying seconds of United's Champions League defeat against Bayern Munich.
Now, the agony!
The club currently refuses to confirm the length of the rehabilitation needed, and will not say when the striker will be able to return to the first team.
Sir Alex will be under enormous pressure to add more detail on the extent of Rooney's injury when he faces the media at tomorrow's press conference, held at the club's Carrington training complex, on the eve of a crucial home match against title rivals Chelsea.
United have had a full day to carry out medical tests on Rooney's ankle. It is unthinkable that Ferguson will try to dodge the two questions United fans most want answered.
The photographs of Rooney leaving Munich on crutches were morale-sapping enough. Immediate press speculation suggested that an absence of two to four weeks was in order. That would sideline the striker for all but the last two matches of United's campaign.
United could still be competing for titles at home and abroad at that stage. Even so, it is hard not to think that Rooney's season is effectively over.
Advanced medical science could restore the Red Kingdom's most talked-about ankle to full working order with only the briefest interruption to Rooney's magnificent season.
The boost to United's challenge for honours would be enormous too, but it may be something of a leap of faith to imagine that Rooney will return immediately as the lethal destroyer of defences who has rubber stamped United's surge in recent months.
That leaves Sir Alex ever more exposed to the folly of Michael Owen's recruitment, sweating on the injury-plagued prodigy Macheda, and reliant on Dimitar Berbatov to fire the team to glory, first against Chelsea and then at home to Bayern.
United can afford to draw against the Londoners and still keep on course for a fourth domestic league title, but they have no room for error when they entertain the pride of Bavaria in the crucial second leg of the Champions League quarterfinal.
Last Tuesday's defeat has been attributed to individual errors, and a generally poor display from a team that was in fine form and had taken the lead.
Sir Alex assures fans that the German side will encounter a more focused United team. He had better be right.
Despite the deserved good press Bayern have received for the manner in which they came back from conceding an early goal, United's players will still be aware that they have rarely been offered an easier route to a European final.
Bayern played well, but were encouraged by a one-paced United midfield which failed to offer sufficient industry or cover.
Worse, the team as a whole revealed a surprising disdain for the controlled professionalism that has distinguished away displays on European nights these past three years.
The Bavarians should be strengthened by the return of two genuine heavyweights in Robben and Schweinsteiger, but the team remains vulnerable to pace. It is also very suspect in defence and a blunt instrument in attack.
If United can play with English tempo, encourage Giggs, Fletcher, and Park to support Berbatov higher up the field, subdue Ribery and close down service to the flanks, they should go through.
With Rooney unlikely to be available, the task is more demanding, but Bayern's coach Louis van Gaal was not indulging in kidology when he declared that United remain favourites to win the match.
Now is the time for United to prove that they are not a one-man team.
A failure to progress would be haunting.