Alex Ferguson will not rest Wayne Rooney with Manchester derby looming Wayne Rooney will not be getting a night off this evening even though Sir Alex Ferguson acknowledges it is his defence that have most to do ahead of Sunday's Manchester derby. In the belief Rooney's fitness levels drop when he misses a game, the Manchester United forward will start tonight's Champions League dead-rubber with CFR Cluj at Old Trafford. More than once this season, Ferguson has raised the issue of Rooney's fitness. And even though the England man's most recent absence with tonsillitis only amounted to two games in the middle of last month, Ferguson is not intending the 27-year-old to be one of the star men who gets a rest tonight. He'll play night and hopefully that brings him on further because Saturday was his best performance of the season so far. But Saturday's 4-3 win at Reading was far more memorable for United's abysmal defending. As has become almost customary, they conceded the first goal. This time though, they fell behind again, even after overturning the original deficit. It means they have now conceded 32 goals this season, their worst performance for 11 years. Ferguson admits it is a concern ahead of Sunday's crucial trip to Manchester City. "If we perform like that on Sunday God knows what's going to happen to us," said Ferguson. The potential for skipper Nemanja Vidic returning to help out should not be dismissed entirely, even though Ferguson's statement on the Serbian's readiness to play after September knee surgery were clear enough. "I don't think Nemanja will play (tonight)," said Ferguson. But if he doesn't play tonight there's no chance he'll play in the derby game, although I wasn't considering Nemanja for Sunday anyway. There is something contradictory about the last statement, especially as the United boss also raised the potential for Shinji Kagawa returning after two months out this weekend, even though Vidic trained with the main group at Carrington yesterday and the Japan international did not.