Sergio Aguero scored the only goal of the game as Manchester City recorded a 1-0 victory over rivals Manchester United yesterday afternoon.

A goal-fest had been anticipated at the Etihad Stadium, but while that didn't materialise, there was still drama courtesy of United defender Chris Smalling, who was red carded for two bookable offences during the first half.

Here, Sports Mole has picked out five of the biggest talking points to have come out of the derby for both teams.

1. Pellegrini still needs "Plan B"

Prior to the match, former United defender Danny Higginbotham stressed to Sports Mole the importance of City manager Manuel Pellegrini coming up with a "Plan B". His reasoning behind such a statement was a belief that the champions had become too predictable to play against, as well as struggling to overturn deficits.

When United had a full compliment of players, there is a case for claiming that they dominated the midfield battle. Indeed, Yaya Toure and Fernando found it difficult to contend with the visitors having a man extra in the engine room. Smalling's dismissal changed the whole complex of the game, so we will never know what would would have happened 11 vs. 11. However, the impression is that Pellegrini would have stuck rather than twist, which may well have proved costly.

For a long time you would have to go back to the days of Mike Summerbee, Francis Lee and Colin Bell to find a period when the Citizens were Manchester's dominant force. Between March 1968 and December 1969, City won four and drew two of six successive derby encounters. Yesterday's win was City's fourth in a row and their sixth in eight meetings with United.

Toure may be struggling to recapture his best form and David Silva may be sidelined through injury, but when fit and available, City can always rely on Aguero. The Argentine went into the clash with five derby goals to his name and nine in the Premier League so far this season.

That form continued at the Etihad. Following a lively first-half showing in which he was denied on a couple of occasions by United goalkeeper David de Gea, Aguero showed his match-winning qualities when he powered in the game's only goal. If he can stay free of injury, City will be believe that they have a chance of claiming three points from any Premier League game.

When Pellegrini recruited Willy Caballero during the summer, question marks where raised over Joe Hart's long-term future with the club. The likes of Iker Casillas and Victor Valdes have also been linked with moves to City in recent months.

However, while Caballero has struggled for form when given an opportunity, Hart proved his worth in the derby. When City came under pressure in the closing stages, England's number one stood firm. One save down low to his right to deny Angel di Maria was a particular highlight.

A defeat would not have ended City's title hopes completely, but that would have left them nine points behind Chelsea. Even at this early stage, with the options available to Jose Mourinho at Stamford Bridge and their current form, it would have been a hefty gap to bridge.

As it is, it's six points that separate the two teams. Pellegrini has been quick to stress that his side are actually better off in terms of points than at this stage last season and with some key players yet to find their best form, the title race is still well and truly on.

1. Van Gaal losing patience with defenders?

Louis van Gaal certainly did not sugarcoat his opinion of Smalling following the centre-back's red card. The Dutchman, notorious for being a harsh critic of his players, branded the 24-year-old "stupid" and "not very smart". United may well have still lost the encounter with 11 men, but Smalling's actions certainly lessened their chances of collecting a positive result.

Van Gaal is also not afraid to be ruthless when it comes to player departures. If his more senior defenders are not making errors, they are ruled out through injury - just as Jonny Evans, Phil Jones and Rafael da Silva were yesterday. With the January transfer window fast approaching, one or two may find themselves heading for the Old Trafford exit door, particularly if replacements can be signed.

Few foreign imports have adapted to the Premier League as quickly as Di Maria - a club-record summer signing from Real Madrid. Yet, when United have needed him in their last two outings against Chelsea and City, the Argentine has been largely ineffective.

In his first few outings in a United shirt, Di Maria flourished as part of a midfield diamond. But, Van Gaal has used the 26-year-old as a wide player recently. Consequently, he has been less involved in the action as his teammates have struggled to get the ball out to him. What's more, being confined to one position makes him much easier to mark.

With Hart impressing at one end, De Gea certainly matched his opposite number between the other set of posts. The Spaniard endured a rocky start to life in England, but that is now just a distant memory. Against City, he showed that there are currently few better goalkeepers in European football with some crucial stops, including one which displayed great bravery in thwarting Aguero.

United, under the management of David Moyes, were mauled in both derby encounters last season. At the Etihad, City ran out 4-1 winners, but had the home side doubled their goal return, United could have had little complaint - such was the gulf in class between the two sides.

This time around, there was more spirit about United - just as there was in the 1-1 draw with Chelsea. Yes, they rode their luck on occasions and could have had two, if not three, penalties awarded against them. Yet, they remained in the game and actually had openings to snatch a point as the game wore on. Those characteristics were missing last term, but there seems to be more resolve about the Red Devils now.

Despite Van Gaal's record with his previous clubs, he's not a miracle worker. Even the most biased of United supporters would surely have not expected United to be challenging for the title along with Chelsea and City. Securing a return to the Champions League was always United's major target.

It means that while a defeat to City is disappointing for the fans, it will not define the season. Whether United finish in the top four will depend largely on how they fare against their fellow competitors for third and fourth spot. In their next six outings, United play Arsenal, Southampton and Liverpool - those are the must-win games.