We know all-too well during the era of the Premier League that while matches between the divisions' leading contenders for the title are decisive in the title's destination, in isolation, the contests represent nothing more than a battle among a war for supremacy in England's top flight.

The battle of the Etihad Stadium ranks among the more entertaining duels between Roberto Mancini and Sir Alex Ferguson in the league. The nature of last season's meetings which saw Manchester City dominate at Old Trafford before showing their nerve on home turf were poles apart and provided evidence that Mancini's side, despite the fine margins involved, were worthy champions come May.

Six points the gap may be, but as last season showed in dispatches, both sides are prone to self-destructing at crucial moments in the campaign, meaning Manchester United's win on Sunday against their nearest rivals is merely a psychological jab rather than knock-out blow.

Robin van Persie
The addition of Van Persie could prove pivotal in the title race.

Many felt the claiming of the Premier League title would be watershed moment in City's history, but instead their first top flight league success in 44 years has acted as a burden on a side yet to get out of the blocks this season. While their Champions League troubles are comparable to last season's strife in Europe, their domestic problems mirror those suffered in Mancini's first full season in charge, with goals few and far between and the onus of resilience rather than style.

It's a guise United have, in recent years, adopted themselves. Gone are the days of the atypical attacking play which defined the early Ferguson years, the modern-day United have concentrated on defensive steel. Second best defensive record in each of the last two seasons, the best in each of the three years previous; even with a front line of Wayne Rooney, Carlos Tevez and Cristiano Ronaldo, their strength came at the back.

This term has been a refreshing about-turn from a United side who have thrown caution to the wind, and while their defensive responsibilities have suffered, it's as exciting a Ferguson team as any during his 26 years in charge.

And even amid the goals (just the 90 in 24 matches this season) United seemingly have the trump card in the Premier League title race. After playing second fiddle in the transfer market to City's monstrous spending power, United salvaged a potentially crucial victory in claiming Robin van Persie from their clutches.

The Dutchman proved to be Arsenal's get out of jail free card last season, and in a title race that even with the six-point gap after 16 games is expected to go to the wire, the £22m Van Persie, as he was in the 92nd minute at the weekend, could be the difference maker.

However, just like the win on Sunday, the successful addition of Van Persie is merely a battle amid the war for the Premier League title. History tells us you write off City at your peril.