The currently fourth-placed team, Liverpool recently had their best result of the season when they tonked rivals Everton 4-0, and there's plenty to be optimistic about. They have the league's leading striker in Luis Suarez, a fine deputy in Daniel Sturridge, and their team appears to be going well. Their weakness is certainly their defence and goalkeeper, but so far the attacking prowess of the team has been able to more than make up for it.
One sour note to an otherwise fine January, at least up until now, however, has been the failure to wrap up a deal for Mohamed Salah. The Egyptian winger looked certain to join the Reds for most of the window until Chelsea suddenly stepped in and concluded a deal to leave Liverpool struggling to find further reinforcements. As a result, the club may find itself struggling as Manchester United at least strengthen their ranks for a renewed charge.
What they also lack is depth - an injury to one of their key attackers would greatly reduce their chances. It's probably that somebody will come through the door this month, but whether it will be the right player is open to debate. Iago Aspas and Luis Alberto were acquired in the summer, but have had very little influence on the season so far. Another mistake like that could be very costly.
A squad that seems to be making less sense every week is still looking some way short of gelling into a cohesive unit, Tim Sherwood is hardly proving himself to be the ideal man for the job, and Spurs look like they may not be able to strengthen in January. Despite all of that, the club sit in fifth, three points behind Liverpool and well in the mix.
Christian Eriksen has probably been the most impressive of those January signings, and he will undoubtedly be key in the second half of the season, not least because of the dearth of creativity coming from elsewhere. Besides that, however, the squad looks like it just about lacks enough to make it. They'll need to hope Sherwood can find some way of coaxing form out of his existing players - finding the perfect role for Paulinho, getting goals from Roberto Soldado, and shoring up the defence are all potential discoveries to be made which could prove decisive.
Of course, with Daniel Levy's name forever tied to deadline day in the British consciousness, it's possible Spurs will end the window with further reinforcements. But they certainly won't be of the calibre of Juan Mata, and with challenges from above in deplacing a resilient Liverpool, and from below in resisting the potential resurgence of Manchester United, Spurs are very much up against it.
While much has been made of Everton's improvement under Roberto Martinez, they are currently sat in the same position they finished last year with a far superior squad, and Manchester United breathing heavily down their necks. Romelu Lukaku's loss of form and subsequent injury will not have helped matters, and the Toffees will need to find a renewed sense of purpose to gain a second wind.
A 4-0 drubbing at the hands of Liverpool revealed the squad's fragilities and weaknesses, and it looks like they could well run out of steam faced with the superior resources of the opposition. In the derby, they dominated possession, but lost heavily as their defence failed to cope with their rivals' pace and skill. True, there were injuries, but there were also injuries to Liverpool, who have a similarly thin squad, and Everton could still not land a glove on a severely stretched defensive line.
If Everton are to find their way back, they'll have to do it quickly. Lacina Traore and Aiden McGeady are additions that could prove to either be inspired or rather anonymous, with neither having any Premier League experience. The upside is that both offer something different which does not particularly need subtlety to be effective - Traore's incredible physical presence and McGeady's skill and trickery. Whether they will be anything other than slightly worse versions of Lukaku and Mirallas, however, remains to be seen.
Manchester United currently sit six points behind, and they have acquired a new and powerful weapon in January to help them make up the deficit in Juan Mata. It is a certainty that none of the other challengers will be able to acquire a player close to being in his class this window, and that could give David Moyes' men the edge.
Injuries have also played a big part in the Reds' lowly league position - Robin van Persie carried the team last year, but has missed too much of this season. On his return, he didn't take too long before putting the ball in the net, and if he were to remain fit for the rest of the season then things would look very bleak for the other fourth place challengers. The return of Wayne Rooney, and potentially Marouane Fellaini finding some improved form, are also potential variables that could swing in United's favour.
But it is Mata that will really be key. United will also almost certainly try to add another name this window, be it a left-back or central midfielder, but even the Spaniard alone should represent a vast improvement. The squad's deficiencies and weaknesses are still there for all to see, but some expensive crack-papering until a busy summer could well see Moyes' men get back in it.