Nemanja Vidic and Anderson have been ruled out of Manchester United's Champions League showdown with AC Milan on Tuesday night.
The pair were missing from the squad that flew out to Italy on Monday morning for the clash at the San Siro.
Vidic, who has yet to play in 2010 after developing a nerve problem in his leg, has been forced out as he is still a way off returning to fitness.
It means United boss Sir Alex Ferguson must decide between Jonny Evans or Wes Brown to partner Rio Ferdinand at the heart of the defence.
Ferdinand is three games into a four-match domestic ban but is available for the resumption of United's quest to reach a third successive final.
It is not known if Anderson has not travelled because of injury as the Brazilian has found himself out of favour in recent weeks.
Ryan Giggs is also missing for United as he recovers from the broken arm he sustained against Aston Villa last week.
Otherwise United have no other injury problems to contend with as they look to gain a positive result to bring back to Old Trafford for the second leg.
United (from): Van der Sar, Kuszczak, Foster, Neville, Brown, Rafael, Ferdinand, Evans, Evra, Fabio, Park, Nani, Valencia, Carrick, Scholes, Fletcher, Gibson, Rooney, Owen, Berbatov, Diouf.