( CNN ) -- Manchester United were dealt a serious blow Tuesday as captain and key central defender Nemanja Vidic was ruled out for at least two months with a knee problem . The Serbian star missed the final five months of last season after rupturing his cruciate ligament and a fresh problem has emerged on the same knee . `` Nemanja Vidic has had a meniscus operation on his right knee and will be out for around eight weeks , '' read a statement on the club 's official website . The new injury setback for the 31-year-old could not have come at a more unfavorable time for the English Premier League giants , who are also missing a number of key defenders ahead of vital league and Champions League clashes . England internationals Phil Jones and Chris Smalling are currently sidelined , the former with the same problem as Vidic , leaving manager Alex Ferguson with only two fit regular central defenders . That includes Jonny Evans , who picked up a minor injury in the 2-1 victory over Liverpool at Anfield Sunday which left United in second place in the early standings . United 's neighbors and EPL champions Manchester City suffered a shock 4-2 home defeat Tuesday to Aston Villa in the English League Cup . City were twice ahead through Mario Balotelli and Aleksandar Kolarov , but two goals from Gabriel Agbonlahor , allied to an own goal from Gareth Barry and an extra time strike from Charles N'Zogbia saw Villa into the fourth round . Meanwhile , league leaders Chelsea continued their fine start to the domestic campaign with a thumping 6-0 home win over second-flight Wolves . John Terry , who quit the England captaincy just ahead of his FA hearing into charges that he made a racial slur in an EPL match last season , lined up for the match at Stamford Bridge . Gary Cahill put Chelsea ahead after just four minutes and it was one-way traffic throughout with Fernando Torres scoring in the second half and new Victor Moses rounding off the scoring . In an all-EPL clash , Wigan won 4-1 at West Ham after the home side had taken an early lead while high flying Everton were shocked 2-1 at Leeds to make a surprise exit .
Nemanja Vidic ruled out for six months with fresh knee injury . Leaves Manchester United short of defensive players . John Terry plays in Chelsea 's famous League Cup rout of Wolves . EPL champions Manchester City beaten by Aston Villa .