Chris Smalling was ruled out for 10 weeks with a broken metatarsal before Manchester United needed a last-minute Bebe goal to avoid a shock defeat to local Ajax side in Cape Town.
Smalling, who remained in Manchester as he team-mates embarked on their tour of South Africa and China in order to reach full fitness after an end-of-season groin injury, suffered the fresh problem in training on Wednesday.
It was immediately decided to send the 22-year-old for surgery, which will keep him out until the end of September.
"He got an injury on the Wednesday and, straight away, we decided to have the operation, so he is out," Ferguson told MUTV, ahead of the game.
"It's difficult to say with a metatarsal but it could be 10 weeks.
"He's not carrying any luck, the kid, but he's young and we have done the right thing in getting it done immediately and getting him back on the road as quickly as we can."
Even if Smalling recovers within the timescale anticipated, it would rule him out until the end of September - a period which encompasses opening six Premier League games, plus the opening UEFA Champions League outing.
In addition, it would condemn Smalling, of whom Roy Hodgson is known to be a big fan, to sit out three England games for certain and, in all probability, October's 2014 FIFA World Cup qualifiers with San Marino and Poland too given the limited time the Londoner would have had to get fit.
The news momentarily took the minds of United supporters off Ferguson's surprising revelation the previous day that he had made a bid for Robin van Persie.
After this game, though, perhaps it is more understandable after the Red Devils failed to exert any significant pressure until the much-maligned Bebe fashioned a response to Alcardo van Graan's smartly-taken goal four minutes from time.
It does seem there is a chance the Van Persie deal might go through, even if the respective clubs are miles apart on valuation.
Of those who appear to have most to lose, Javier Hernandez must be one.
After an outstanding debut campaign, the Mexican faltered last term, scoring just 12 goals.
In barring Hernandez from Olympic duty, Ferguson was making it clear the forward would benefit from his first proper pre-season as a United player.
After a sluggish contribution to the midweek win in Durban, Hernandez was a bit livelier here, rising to meet Antonio Valencia's far-post cross, only for former Liverpool goalkeeper Sander Westerveld to palm it away.
Hernandez just failed to reach a delicate Michael Carrick throughball, which more or less wrapped up United's threat on the home goal as Shinji Kagawa eased his way through a first start where he looked good in parts but gave the impression he will need to bulk up for Premier League duty.
The Japan star was presented with an outstanding opportunity by Hernandez after an hour but he guided a free header wide.
Fellow new boy Nick Powell was given 25 minutes to impress in central midfield.
It was the introduction of record signing Dimitar Berbatov that really livened the 50,000 crowd up, though Van Graan threatened to emerge the hero until Bebe struck at the far post.
English Premier League