Alan Hansen believes Manchester United's recent woes are being exasperated by Sir Alex Ferguson's lack of a Peter Schmeichel or Edwin Van der Sar.

Where Manchester City have England's number one Joe Hart, Manchester United have perennially juggled the precocious David De Gea and Anders Lindegaard.

Neither of the aforementioned Manchester United custodians have successfully usurped Van der Sar's undisputed role at Old Trafford and Sir Alex Ferguson appears uncertain about who his first choice stopper is, which merely serves to heighten the ambiguity undermining the Red Devils' back-four this season.

Hansen believes the goalkeeping position is generally a measure of a side's title credentials, and at the minute Manchester United are struggling to replace one of their club's finest ever.

"The importance of a reliable goalkeeper has been emphasised on both sides of Manchester this week." Hansen explained to the BBC.

"Joe Hart played a crucial role in City's win against Liverpool with an early save from Stewart Downing and some fine handling in dreadful conditions, while Ferguson dropped David de Gea, his £17m summer-signing from Atletico Madrid, for the game against Newcastle after the Blackburn defeat.

Citing some of Manchester United's most illustrious goalkeepers, Hansen believes Sir Alex Ferguson no longer has a player capable of winning games on his own, like the aforementioned Dutchman who retired last season.

"Goalkeepers like Peter Schmeichel and Edwin van der Sar - who was so good last season you wonder why he retired - made the saves that won matches and kept Manchester United in competitions." Hansen continued. "De Gea was making mistakes that were costing goals so, eventually, Ferguson decided to go with Anders Lindegaard."

The Match of the Day pundit, who won eight league titles during his trophy laden Anfield career, believes the injuries to their defensive line and in particular Nemanja Vidic, has exasperated their problems in goal.

"Manchester United have also had problems in defence. They haven't had a settled back four and the absence of Vidic has compounded this. Their last two games tell you all you need to know about the consequences.

"When Vidic was playing, he was the best central defender in the Premier League; now he is not, that mantle can pass to Manchester City captain Vincent Kompany."

While eager to champion Manchester City and Manchester United's respective captains as the finest centre-halves in the division, Hansen believes this weekend's FA Cup tie at the Etihad Stadium could have wider implications in the Premier League title race.

"It will be a huge occasion on Sunday and the sort of game a wonderful competition like the FA Cup deserves - but there could also be wider significance for the Premier League in how it plays out." Hansen concluded.

Manchester City welcome their bitter Premier League rivals in the FA Cup third round on Sunday, and Roberto Mancini fears he may not be able to fill his whole quota of substitutes against Manchester United.

"For Sunday (against Manchester United), we have 17 players and I don't think we will fill the bench," he said. "In January - and I said this two months ago - we could have a big problem."