Will City mauling bring about changes at United? Fans will want to see a reaction and an apology ...

Manchester United and Sir Alex Ferguson finally ran out of luck today at Old Trafford in the worst possible manner and as far as the fans are concerned against the worst possible opponents, neighbours Manchester City. United lost 6-1, yes, that's right, six bloody one. It is the biggest home defeat since 1926 when the blues repeated that scoring feat.

The final scoreline and especially the manner of the second-half 'performance' has rocked Old Trafford to its foundations. City took United apart in the second-half, with ruthless professionalism and efficiency. City took an early lead against the run of play with a Mario Balotelli goal, Jonny Evans could have and perhaps should have been closer to the City striker, but the Italian's cool finish was that of a player bang in form.

United tried to hit back, but could find no way through City's well organised defence. Time and time again, United's attacking moves broke down on the edge of the City penalty area - that was the story of the champions first-half performance. United simply didn't have the guile or know-how to unlock City's packed defence.

United have been blowing hot cold this season, but over the last few weeks the defence that has been the bedrock of so much success has looked anything but solid. Even before today we've seen visiting teams exploiting the wide open spaces in front of United's back-four. Basel did it in the Champions League when coming back from two-nil down to lead 3-2. Norwich were unfortunate to lose 2-0 recently and prior to that, and as totally ridiculous as they may sound (to those with short memories) Arsenal missed a catalogue of chances in that 8-2 mauling and who would have predicted today's outcome after that result? Not many.

Given the manner of United's defending in recent weeks, it came as no great surprise to see Mancini's team come to Old Trafford today with a simple game plan, one that involved not conceding and hitting United on the break. It's a tactic that United themselves have used many times away from home, under Ferguson down the years, but today the champions were on the receiving end and the final score did not in any way flatter the visitors who were good value.

The turning point of today's derby came in the 46th minute, when Aguero and Balotelli combined with a smart inter-change of passing outside the United penalty box, which left Evans isolated and up against City's Italian striker. Fearing Balotelli was going to out-pace him, the Northern Ireland international grabbed the Italian's arm and referee Mark Clattenburg had no option but to brandish his red card.

From that point on, City made good use of the extra man, but without really forcing the pace of the game; the visitors simply carried on waiting for their chances on the break, and sadly for the home supporters, all too often United were guilty of gifting possession back to the league leaders. It was all a bit too easy for City and that in part made it even harder to stomach.

City eventually made their dominance pay with a very well worked goal and once again it was Balotelli who did the damage, but as on so many other occasions this season it was David Silva who was the architect. Silva was outstanding again for City and any honest United fan would tell you that they'd love to see the mercurial Spaniard in the famous red shirt. But United simply don't have a David Silva and how Ferguson must regret never making a move for him when he had opportunities in the past.

City sealed the win on 69 minutes thanks to Aguero with another well worked goal. Darren Fletcher scored what turned out to be nothing more than a consolation goal, albeit a very good one, but the joy of scoring was short-lived as City really took United apart as they went on to hammer three more nails in the champions coffin with a brace by substitute Dzeko and goal by the man of the match David Silva.

Until this week, Fergie hadn't really given City and Mancini that much credit, and when he has given credit it has been through gritted teeth. Going into today's derby, one had the sense that many United fans feared losing this game, but no one will have anticipated such a heavy defeat.

The worry perhaps for United fans is that such defeats can have far reaching consequences. On the face of it, United have been doing well with good wins against Arsenal, Chelsea and a creditable draw away at Anfield, but following a run of indifferent performances the early season optimism has worn off.

Going into the season many fans and pundits voiced concerns about a perceived lack of genuine star quality in the United engine room. Granted, Tom Cleverley was doing very well, so good in fact that he confounded many of those critics, but that was prior to the clumsy intervention of Bolton's Kevin Davies whose rash tackle at the Reebok left the rapidly rising midfield star on the sidelines. No doubting many United fans will have been left wondering if Cleverley might have made a difference today, if he'd been 100% fit to play. We will never know.

What we do know is this, thrashings of the like we saw today, can have short to medium term affects on the team, the players and even the manager. Take the recent 8-2 hammering of Arsenal, the Gunners haven't really recovered from that stuffing, the growing calls for WengerUnited's confidence could be badly affected following such a heavy derby defeat.

Nonetheless, what happened today at Old Trafford could potentially have implications. In his post-match interview, Fergie says that he was 'shattered' and he also pointed the finger squarely at senior defenders Rio Ferdinand and Patrice Evra for allowing United to continue to attack City at a time when the champions were a man down. United have a reputation for pulling off sensational comebacks, and on countless occasions Fergie has stated that his team only knows one way of playing and that is THE UNITED WAY, which is to "attack, attack, attack, attack, attack". United tried to attack City today, but once Evans went off City really took control and made the champions look second best in every department and that was another very worrying aspect of what we saw today.

So what if anything, can Fergie do about the current situation? The manager quite evidently needs to add some genuine star quality in central midfield. As we saw today, United quite evidently do not have quality strength in depth in central midfield, but those who believe in Michael Carrick, Anderson and Darren Fletcher might argue otherwise.

Whatever anyone says, United do not have a player of the quality of David Sivla. One might also ask questions about the strikers. Danny Welbeck has done really well so far this season, but would he get into City's first-team, or even Chelsea's?

While it's obvious that City can out-spend their rivals and we have to acknowledge there is no easy answers for the manager, perhaps after this soul-searching defeat, Fergie and his backroom team will have to think about a change in formation and tactics. United have looked far too open this season and this isn't just a knee-jerk reaction to today's embarrassing defeat, it has been blindingly obvious over recent weeks. Perhaps worryingly, one suspects Fergie himself has been saying the same things to his team...

If what happened today does not bring about some changes both in terms of personnel and possibly changes in tactics, then this blog will be very surprised indeed.

Fergie and his backroom team may well conclude that we need to get back that continuity in the key central defensive positions, that is likely to be a starting point in the post-mortem and the resulting action plan that is sure to follow.

Fergie and the fans might also wonder what might have happened if Evans had stayed on the pitch, but we are only kidding ourselves if we believe that we can continue to keep pace with City if we don't add more quality. Whatever else happens in the weeks and months ahead, United fans will be looking for a reaction from the team and an apology from the players for what happened today, it is the least we should expect.

Even if United go on to win the title, what happened in today's derby will not be forgotten for a very long time. Fergie, Fergie, sort it out.