While "if they sort their away form out..." was a much-heard refrain when discussing City's title chances, their invincibility at home was always just as likely to be the variable to change. City are still unbeaten, and the last team to keep a clean sheet there remains Alex McLeish's Aston Villa, but their victories have been a lot less impressive lately, and they were fortunate to get past Crystal Palace.
Their summer signings seem to have been by far the best of the top teams, with Alvaro Negredo continuing to impress, Fernandinho looking better with each game and Jesus Navas growing into his role too. Combined with Sergio Aguero potentially ascending into the ranks of the world's top strikers, City have more cause for optimism than anyone else.
It is debatable that the club will do much significant in January, or will need to — an improvement on their team would need to be a pretty significant purchase, which mid-season could risk destabilising a winning side. Their away form still needs improvement, but right now they look the most dangerous team in the league whether at the Etihad or not. The team to beat.
José Mourinho pioneered 2-0 wins as the bedrock of a title victory, but whether he can do the same with 2-1 wins will be the key to Chelsea's challenge. They certainly have done so far, with the difference being that when his old team beat teams 2-0, they were well beaten — that comfort can occasionally come in a narrow win where the other team is not given a sniff, but some of the Blues' victories this season have resembled nothing of the sort.
Yet if managing to win games while not necessarily playing well is the mark of a champion, can the same be said of managing to win games when you're genuinely terrible? Despite the flaws in Mourinho's side (a dysfunctional midfield, dodgy centre-backs, poor strikers), his side still sit well-positioned in the league, and has managed to get just enough out of the likes of Eden Hazard and Oscar to keep his team winning games.
The problems are far too many to be solved in the January window. But just sorting out one or two could well put the Blues in a position to play better. Of all the top teams, only they and Manchester United have shown the sort of fight to come back from losing positions, rather than other sides simply turning up, failing to click, and having no idea what to do about it. But Mourinho's men have also had the resilience to defend their leads — that mentality married to the skill and quality in the squad has carried them so far, and with fewer problems, it could be enough to win them a title.
A pretty disastrous start to the David Moyes era at Old Trafford meant that the last few weeks were pivotal, and Alex Ferguson's successor has managed, with key injuries, to get the most out of his squad and drag his side back into contention. This was no mean feat, with United struggling for any sort of fluency and still reliant on the absent Robin van Persie, but some excellent squad management and decisions have not only ensured United are closer to their usual position, but also suggest that Moyes has gotten to grips with the squad at his disposal.
United are not the likeliest to win the title, but they have advantages over their rivals. Unlike Arsenal, they are unlikely to face a horrible run before the season's end, which will finish them. Unlike Manchester City and Liverpool, they have shown the fight to come back from losing positions. And unlike Arsenal, they have world-class attackers and a solid defence which has been the root of their success previously.
Above all though, is the prospect of January. Many teams will view the window as key to their success in the title race, but it looks likely that United will be the biggest spenders and the team that have the most capacity to improve. They've gotten where they are without a midfield and with barely a functional winger — one of each could make a colossal difference to the side and make them very difficult to stop.
Arsenal's now-traditional implosion is still expected by many, and largely justified by the incredible difficulty they face in February and March, where they will likely have to go on a superhuman run just to emerge level with their rivals at the end. There are other reasons to doubt them: Olivier Giroud is surely not clinical enough for a team that has designs on competing at the highest level, and their defence looks a different, lesser beast in big games. Mesut Ozil could revert to his brilliant norm, but there are far more players overperforming in this side who could equally revert to mediocre type.
Yet the mental fortitude that the team appeared to discover at the start of the season has not gone away. The 1-0 victory away at Newcastle was typical for prospective champions, and for Arsenal, being outplayed and managing to win regardless is a huge and promising step. That didn't happen before, but collapses did. This year could be different, but they'll need to move very carefully in January, have a run of imperious form, and keep playing at a level above the quality in their squad. Conversely, at least two of their competitors are certainly playing within themselves. It doesn't look likely.