Perhaps the moment when Manchester City turned into a genuine threat to Manchester United's superiority was the FA Cup semi-final in 2011, where Yaya Toure's strike proved the difference between the two sides. In intercepting Michael Carrick's stray pass and bursting forward with his physicality, Toure illustrated the key difference between the two midfields in recent years - one based around power, the other around precision passing.
That was, at least, until deadline day, when United's late swoop for Everton's Marouane Fellaini changed the dynamic in their midfield zone significantly. No longer is it simply about Carrick's ability to hit clever passes into the feet of the advanced players, to trigger attacking moves, and his complete lack of a competent partner: instead, now there is the additional threat of the strong, tall Belgian.
Fellaini's emergence into a top-tier talent is an intriguing one. His signing is predicated on his 2012-13 form, but he won't play the position he was so impressive in. Instead, rather than being used high up the pitch, using his combative hold-up play as the anchor for attacks, he'll become United's deep-lying midfielder alongside Carrick, adding the defensive shield that many have so long bemoaned has been missing from United's midfield. His capabilities in fulfilling the second striker role once occupied by Tim Cahill at Everton masked Fellaini's personal desire to play deeper in midfield, where in his own words "I know my job when I play there... more things are in front of you."
However, it would be a shame if Fellaini's attacking instincts - or at least, his ability to work from box-to-box - were sacrificed in order for him to stay deeper and allow United's attackers stay higher up the pitch, which was the case in Wednesday's Champions League tie against Leverkusen. He rarely strayed forward, staying in deeper positions and shuttling balls forward into the feet of the ever-moving Robin Van Persie and Wayne Rooney.
It's difficult on the basis of one game to ascertain whether United's midfield dynamic is really ideal but the Manchester derby provides almost the perfect litmus test. Interesting, Manchester City's own Yaya Toure is experiencing a similar shift in style. Manuel Pellegrini has asked him to play as the deeper of the midfield two, with Fernandinho given the greater licence to burst forward. Therefore, Toure's completed more passes per game than any other player in the Premier League this season, frequently dropping in between the two centre-backs and keeping his distribution short and tidy.
The memories of Toure gliding past defenders with incredible upper body strength are thrilling and it would be a shame if he and Fellaini - both previously having impressed in advanced roles but now being asked to play more defensive - were asked to curtail their attacking instincts for the derby, rather than clash directly in a very literal midfield battle.
However, given the tendency of both Moyes and Pellegrini to play pragmatically in big games, you feel this won't be the case. Instead, two of the Premier League's most physical, powerful midfielders will likely play calmer, defensive roles - perhaps the best way for both managers to get the best out of their other attackers, even if it is at the expense of Fellaini and Toure's individuality.