Countdown to the derby: Ian Hawkey compares the impact of each side's defence on their Premier League title bid.
City v United: Attacking prowess has covered up frailties at the back
This has not been a vintage season for defenders in the Premier League.
The 20th edition of the self-styled most popular domestic competition in football will be remembered for its derby denouement, specifically, but also for the dazed faces worn by so many elite footballers after some of the several bizarre scores that littered its weekends.
One of the peculiarities of English football is the high proportion of former, illustrious defenders who analyse and cast opinions on matches from television studios, men like Alan Hansen, once the rock of a successful Liverpool, Martin Keown or Lee Dixon, members of famously miserly Arsenal defence, and Gary Neville, the former Manchester United full-back.
The United who currently sit top of the table will probably not finish the season with the best defence in the land. Nor would they need to, as Neville will remember from his career there.
United work with a manager who knows firepower can compensate for a less-than-hermetically sealed back four. United won their last Premier League, 12 months ago, having conceded very close to an average of one goal per game.
That is a high quotient in modern football. Juventus are currently on course to win the Serie A title having conceded a mean of 0.53 goals in their unbeaten league campaign so far.
Granted, Italian football retains something of its traditional emphasis on tidiness at the back. Which may explain why under their Italian manager Roberto Mancini, City will probably end up with a superior defensive record to that of United for the second season running, even if, again, they finish below them in the table.
Mancini came to English football with three league titles under his belt, won with Inter Milan, a fame as a gifted creative inside-forward from his playing days but a well-earned reputation for valuing fortitude over flair. Among his chief allies at Inter had been hardened operators like Marco Materazzi, Ivan Cordoba and Walter Samuel.
Other than Kolo Toure, City cannot call on the range of experience those men had. Nor did Mancini interpret the high-speed pinball of Premier League penalty areas as an area requiring veterans.
The older Toure brother has had a chequered time under Mancini, who urged his board to invest heavily in a new centre-half and a new left-back in both the summer transfer windows he has been involved with as City boss.
In the first, Jerome Boateng and Alexander Kolarov arrived; in the next, Boateng returned to Germany and Stefan Safic and Gael Clichy came in. Only Clichy, of the Mancini era newcomers, can claim to have won the manager over. Savic has been a disappointment.
City's most effective central defensive partnership is that of the mobile Vincent Kompany with Joleon Lescott. Micah Richards, the athletic right-back, has also made progress this season after a period when his career seemed to have stalled. Yet both he and Clichy, who like to advance, can appear over-cautious about advancing.
"You only need seven men going forward when you attack," Mancini told his team after defeat at Sunderland in the new year. Being caught on the counter is a special phobia of his.
Kompany was the only defender from either of the Manchester clubs named in the PFA's XI of the season last week. He had been in that select, notional team, voted by his peers, 12 months earlier, too, alongside United's Nemanja Vidic.
Should United seize the title, the achievement should be valued all the more highly because they will have done so without Vidic since the knee injury he sustained against Basel in September.
That was not an edifying night for United, defensively, as they crashed out of the Champions League unusually early. Ajax and Athletic Bilbao would also find them frail. At left-back, Patrice Evra has not had his best campaign in a United shirt, though competition for his place is limited. Question marks over right-back Rafael's positional discipline remain.
Ferguson has praised Jonny Evans in recent weeks for his performances alongside Rio Ferdinand in Vidic's absence, but there is little doubt United's back four is a work in progress.
Vidic and Ferdinand, at their peak, would rank among the treasured centre-half pairings of Ferguson's long career, alongside Willie Miller and Alex McLeish at his Aberdeen of the 1980s, or Steve Bruce and Gary Pallister at United in the 1990s.
The manager's hope is that one day Chris Smalling and Phil Jones might create the same aura and, above, that there will not be another season during which seven different opponents - City, Chelsea, Basel, Newcastle, Blackburn, Ajax and Athletic - score three or more goals against United.
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