Arsenal, Leicester, Manchester City and Tottenham are the top four teams in the Premier League heading into the new year.
Here, Press Association Sport looks at what they need to do to if they are to push for the title in the second half of the season:
ARSENAL (1st, 39 points)
With Chelsea out of the running, and Manchester United unlikely to challenge this year, Arsenal will not have a better chance of winning the title. The Gunners have had some impressive results in the first half of the season. They blew Manchester United away, scored five at Leicester and produced the most unlikely of comebacks to make the Champions League knock-out stages. But nagging doubts about Arsenal's title credentials came to the fore when they lost 4-0 at Southampton. Mesut Ozil is producing the best form of his Arsenal career, Alexis Sanchez has scored nine goals so far this season and his work rate is phenomenal, while Hector Bellerin and Nacho Monreal have become possibly the strongest full-back pairing in the division. With Jack Wilshere and Danny Welbeck to come back from injury, this could well be the season Arsenal end what has become a 12-year wait for the title.
WHAT THEY NEED TO DO IN JANUARY: Buy a defensive midfielder and a striker.
LEICESTER (2nd, 39 points)
Many tipped the Foxes for relegation, but Claudio Ranieri has continued the good form Leicester produced under Nigel Pearson towards the end of last season. In 2015 they won half of their league matches and only lost nine. Leicester began the year at the bottom of the table, but are a changed team. A testing stretch including games against Tottenham, Liverpool, Manchester City and Arsenal lies ahead. If Ranieri's side come through that period unscathed - and reinforcements arrive in January - perhaps Leicester really could complete the biggest shock in Premier League history by lifting their first title.
WHAT THEY NEED TO DO IN JANUARY: Keep hold of Jamie Vardy and Riyad Mahrez. A centre-back is also a priority as there is no guarantee Wes Morgan and Robert Huth, who have a combined age of 62, will last the distance.
MANCHESTER CITY (3rd, 36 points)
Many thought Manuel Pellegrini lacked the charisma to take City to the top again, but the Chilean oversaw five straight wins at the start of the campaign. Since then, City have been inconsistent, however. They have handed out a number of thrashings, most notably to Newcastle, Sunderland, Bournemouth and Crystal Palace. But they suffered damaging 4-1 defeats to Spurs and Liverpool and could also manage just a 0-0 draw at Aston Villa. Tuesday's goalless stalemate at Leicester showed City lack a Plan B when Sergio Aguero is not firing on all cylinders. Wilfried Bony is simply not up to the task. Kevin de Bruyne and Raheem Sterling will chip in with goals now and again, but extra fire-power may be needed if City are to top the table come the end of May.
WHAT THEY NEED TO DO IN JANUARY: Sign another forward and a centre-half.
TOTTENHAM (4th, 35 points)
Tottenham manager Mauricio Pochettino has jettisoned most of the expensive imports bought with the money from Gareth Bale's sale and promoted hungry home-grown talent. After an early wobble, Harry Kane has found his form, and Eric Dier has matured into a commanding holding midfielder. In Dele Alli, Pochettino has landed one of the signings of the year. The 19-year-old is a robust, aggressive midfielder with an eye for a pass and a clinical finish. His international debut against France was one of the best performances by an England midfielder in the last few years. Spurs also have the best defensive record in the league. Toby Alderweireld has proven to be a shrewd purchase and Hugo Lloris continues to be one of the best goalkeepers in the division. Pochettino also seems to have instilled a great work ethic at Spurs which will be key if they are to challenge for top spot.
WHAT THEY NEED TO DO IN JANUARY: Buy a striker to ease Harry Kane's workload.