(CNN) -- Nemanja Vidic has been ruled out of Manchester United's Champions League trip to Wolfsburg on Tuesday, leaving manager Alex Ferguson with a threadbare defence as his team attempt to secure top spot in Group B.
United had hoped Vidic would have recovered from the virus that kept him out of Saturday's Premier League win at West Ham.
However, the Serbian was absent as the squad checked in for the short flight to Germany, giving their manager a major headache.
His list of injured defenders includes England internationals Gary Neville and Wes Brown, who both limped out of Saturday's game, plus longer-term defensive casualties Rio Ferdinand, John O'Shea and Jonny Evans.
With Brazilian Da Silva brothers, Fabio and Rafael, also sidelined, the only orthodox defender Ferguson has in his squad is left-back Patrice Evra.
Ferguson has already revealed his intention to play midfielder Michael Carrick in central defence while another midfielder, Darren Fletcher, seems certain to occupy a defensive berth too.
In addition to the defensive problems -- first-choice goalkeeper Edwin Van der Sar is also missing -- Ferguson has taken the option of leaving strikers Wayne Rooney and Dimitar Berbatov at home, meaning Michael Owen and Danny Welbeck are the only forwards in his 19-man squad.
Given Bundesliga champions Wolfsburg are unbeaten at home in this season's competition, it would appear United's best hope of finishing top would be for CSKA Moscow to defeat Besiktas in Istanbul, which would leave the United at the head of affairs no matter what their result is.