Manchester United defender Nemanja Vidic is set for a 10-day spell on the sidelines after tweaking a nerve in his leg before the FA Cup defeat to Leeds.Manager Sir Alex Ferguson admitted he was not sure why Vidic had missed the game after pulling out in the warm-up. [LNB]The Serbian, 28, will now miss Saturday's trip to Birmingham as well as the clash with Burnley next weekend. [LNB]Ferguson said: "We sent him to a specialist on Wednesday and the problem will be solved by some exercises." [LNB]The mystery surrounding Vidic's withdrawal before Sunday's FA third-round tie led to speculation the defender was unhappy at Old Trafford. [LNB]Rumours surfaced that a move to Real Madrid could be on the cards but were subsequently diffused when Vidic insisted he had a "marvellous relationship" with his boss. [LNB]Ferguson added: "He felt a bit of a problem with the right side of his leg and didn't feel confident about playing the game. [LNB]"I understand that because it was quite painful. He should be back in about 10 days' time." [LNB]The Serbia international, rated as one of the best centre-backs in the world, cost United £7.2m when he moved from Spartak Moscow at the end of 2005.[LNB]Veteran right-back Neville has been plagued by injuries in recent seasonsHe has been a big success at Old Trafford, but speculation that his wife Ana is unhappy in the north-west has persisted. [LNB]Ferguson has had to deal with a host of injury problems recently that has sidelined the majority of his first-team defenders. [LNB]The United boss said on Friday that England centre-half Rio Ferdinand was two weeks away from a return to action. [LNB]Meanwhile, Ferguson also dismissed as "a load of nonsense" reports that Gary Neville will retire at the end of the season. [LNB]Neville, who celebrates his 35th birthday next month, has endured three seasons interrupted by injuries. [LNB]The right-back was disappointing in the 1-0 defeat against Leeds, leading to speculation of an imminent retirement. [LNB]But Ferguson said: "There has not been a decision about Gary Neville. [LNB]"Why make a decision about his future when we don't need to? You don't make decisions like that in the middle of the season. It is a load of nonsense."