With John O’Shea playing against Fulham on Saturday, there’s still a good chance the Irishman may be preferred at right back to Rafael who was stretchered off at Stamford Bridge.
“Rafael did a bit of jogging on Monday morning,” said Ferguson.
“Hopefully he will be able to be ready for Tuesday but I am not sure about it.
“There is a little doubt and it is not something I want to be risking in a major game.
“He really has to do something special on Tuesday morning to change my mind about it.”
Speaking of United’s form which has seen The Reds win six games on the spin, Sir Alex said:
“Momentum is key, when you get that momentum it is difficult to knock you off your stride.
The United boss was also quick to warn that the tie may be more difficult for his side due to Chelsea being a lot more used to coming to Old Trafford than other European sides.
“A British team coming here is different , though Juventus and Milan have played here a few times over the years, Chelsea play here every year.
“In that respect there is a familiarity about it. The stadium, the size of the pitch, the condition of the pitch all these things are in their favour over other European teams.”
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