The January transfer window is now open, giving sides the chance to boost their squads for the second half of the season.
Who is on the move, and will any of the Premier League's top clubs be busy? ESPN FC's club correspondents have a look ahead at what could be a pivotal month in the season.
What's needed this month? It seems greedy to want to add to a squad that is so far ahead of everyone else in the Premier League, but City will want to, particularly if they are going to challenge for the Champions League. City started the season with only one recognised left-back in Benjamin Mendy, and the French international is estimated to be ruled out until around April. However, Fabian Delph has been a huge success as a backup, and Pep Guardiola appears to see centre-back as a more pressing need.
Likelihood of business being done: 8/10. Pep Guardiola wanted a new centre-back in the summer, and he was close to signing Jonny Evans from West Brom on transfer deadline day. His main concern was over his backups to first choice defenders John Stones and Nicolas Otamendi, with doubts over the fitness reliability of Vincent Kompany and quality of Eliaquim Mangala. Neither player has successfully eased those concerns, and it's possible that Mangala could leave the Etihad in the transfer window to make way for a new arrival.
Pick a target: Southampton's Virgil van Dijk was among the centre-back options being considered, but with the Dutch international moving to Liverpool, City could now return for Evans. He has many qualities, which would suggest he would be a useful addition to Guardiola's squad. He's comfortable with the ball, has plenty of high-end experience from his time at Manchester United, will be eligible to play in the Champions League and will also qualify as a homegrown player. However, the Northern Ireland international turns 30 on Wednesday, and City won't want to spend too heavily on a player who is unlikely to have any resale value.
Predict a move: Mesut Ozil to Manchester United. Jose Mourinho has indicated that he is not satisfied with the depth of his squad and lacks creativity. Ozil is someone he knows from Real Madrid, and with the German out of contract at the end of the season, a deal could suit both Arsenal and United.
What's needed this month? Ashley Young and Luke Shaw are doing well enough that buying a new left-back can wait. But Jose Mourinho wanted Ivan Perisic in the summer, a right-sided wide player, and he will probably think his squad is still missing that type of attacker. He could also do with a No.10 he trusts. Henrikh Mkhitaryan has fallen down the pecking order, and Juan Mata plays on the right. Jesse Lingard has done well in the past month, but he is not in the mould of Ozil or Wesley Sneijder -- two players who shone for Mourinho in previous jobs,
Likelihood of business being done: 5/10. United call the January window an "opportunistic market," meaning that, while they are not planning to buy, they are ready to take advantage of a situation that may present itself. They will not buy for the sake of it, but if they can get a summer target in at a reasonable price, they are prepared to do it. Last January, United sold Memphis Depay and Morgan Schneiderlin, and there is a chance, albeit quite slim, that fringe players Daley Blind or Matteo Darmian could leave if they ask for a move.
Pick a target: Ozil's contract situation will be interesting to United. He's a player Mourinho knows well, and United need a No.10. Arsene Wenger has insisted Ozil won't leave in January, but if that stance softens and Arsenal are prepared to listen to bids of around £20 million, there is a chance it could happen. It is still more likely that Ozil leaves for free at the end of the season.
Predict a move: Alexis Sanchez to Manchester City. And it should worry United that a team already streets ahead in the Premier League is looking to strengthen.
What's needed this month? Antonio Conte wants to improve his Chelsea squad "in the numerical aspect," so more depth is the order of the day. The most pressing need is a natural alternative for Marcos Alonso at left wing-back, but an established central striker and wide forward would also allow Michy Batshuayi and Charly Musonda to leave on loan in search of regular football.
Likelihood of business being done: 8/10. A troubled summer laid the foundations for Chelsea's setbacks and Conte's frustration this season. The club hierarchy know they must explore all options in the winter market, and if there is a deal to be made, Marina Granovskaia has proved better than most at getting it done. David Luiz's future remains a question mark after his clash with Conte, but the Italian will not agree to any significant departures unless replacements are secured first.
Pick a target: It's no secret that Conte desperately wanted Chelsea to sign Alex Sandro last summer. Juventus refused to countenance a sale then, but the Brazilian has struggled to find his best form since, and there have been suggestions that a deal could be possible in January. The reported asking price of around £52m, however, seems steep when Alonso is performing well as first choice.
Predict a move: Now that Liverpool have taken Van Dijk off the market, Manchester City will have to look elsewhere if Guardiola wants to strengthen his centre-back options in the January window. West Brom captain Evans emerged as a target in the final days before last summer's deadline, and it is not difficult to imagine him proving to be a reasonably priced and very gettable prize for the runaway Premier League leaders this time around.
What's needed this month? A new centre-half has been required at Anfield for some time now, but Liverpool already addressed that need with the acquisition of Van Dijk prior to the window even opening. Focusing on other areas, if Liverpool are to win their first Premier League title anytime soon, then they need to assess their goalkeeping situation. And despite boasting one of the best frontlines in Europe, Jurgen Klopp attempted to bolster it in the summer with Thomas Lemar, suggesting the Reds boss wants more match-winners on his books.
Likelihood of business being done: 5/10 (after Van Dijk). As seen in the summer, Klopp has his eyes fixed on his prime targets and often won't settle for second best in alternatives. Despite attempts to do more, Van Dijk will become the German's first January signing as Liverpool manager, having found signing elite players midway through a season to be difficult task. Expect to see plenty of players -- possibly Danny Ings, Ben Woodburn and Marko Grujic included -- head out on loan.
Pick a target: Liverpool made a late push, along with Arsenal, to sign Monaco's Lemar last summer. The line from Monaco's hierarchy recently has been that the French international will not be departing in January but could potentially leave in the summer. Lemar hasn't hit the same heights as last season, scoring just twice in 2017-18 so far. However, a promising World Cup campaign for the 21-year-old may increase his price tag, making a summer move more likely.
Predict a move: Confirmation of Emre Can's move to Juventus next summer. In January, Can will be able to agree to a deal in principle to join a European club, with his Liverpool contract expiring at the end of the season. The Italian champions have courted the midfielder for a while now, and it seems like it's only a matter of time before the topic of his future is finally settled.
What's needed this month? If Toby Alderweireld and Victor Wanyama return from injury unscathed, Spurs don't need much in the January window. They could still do with a speedy wing-forward in the Wilfried Zaha mould, while a more technical version of Moussa Sissoko would add quality to the midfield. Fernando Llorente has not impressed as Harry Kane's deputy, but they are likely to persist with the Spaniard until the summer. Spurs need to buy British, as they have maxed out their foreign player quota in the Champions League.
Likelihood of business being done: 3/10. Spurs have not made a January signing since Dele Alli (who was immediately loaned back to MK Dons) in 2015, and Mauricio Pochettino has already said they are likely to have another quiet winter window. However, the Spurs manager did suggest that the club could try to steal a march on their richer rivals by agreeing to more deals like Alli's for next summer, while chairman Daniel Levy is always in the market for a bargain. Josh Onomah and Cameron Carter-Vickers may be recalled from loans to boost the squad. It's unlikely they will sell anyone, although Georges-Kevin Nkoudou is expected to leave on loan.
Pick a target: Ross Barkley. Remember him? Pochettino is a long-term admirer of the Everton midfielder, who has been injured all season, and it is believed Barkley is interested in working with the Argentine. Spurs could try to sign Barkley on a pre-contract agreement or for a cut-price fee in January, but they will surely face competition from Chelsea, who agreed to a deal with the Toffees on transfer deadline day in August, only for Barkley to reject the move. At this stage, it may depend on which club can better guarantee him minutes and boost his World Cup hopes. Wanyama's injury woes and Mousa Dembele's continued creaking mean Spurs could offer him plenty of playing time.
Predict a move: Zaha to Manchester City. They can start doing what Chelsea used to do and buy players that they don't need just to stop their rivals from signing them.
What's needed this month? Clarity. Arsenal need to decide who is staying and who is leaving as soon as possible, then find replacements if necessary. If Ozil and Sanchez both see out their contracts, it's hard to see Wenger spending big until the summer. A holding midfielder remains the team's biggest need, but that hasn't been addressed in years and probably won't be now.
Likelihood of business being done: 7/10. Mathieu Debuchy is the most likely departure, while you can't rule out either Olivier Giroud or Theo Walcott exploring their options.
Pick a target: Arsenal could go back for Lemar but are unlikely to match the £90 million bid they made this summer, making a deal improbable. Julian Draxler is a more likely target as Paris Saint-Germain could be willing to offload him.
Predict a move: Mathieu Debuchy finally finds a buyer and leaves Arsenal.
What's needed this month? Despite spending more than £200m during the brief Ronald Koeman tenure, Everton remain in possession of a terribly unbalanced squad that still needs significant fine-tuning. Leighton Baines is the only recognised left-back, and his recent trend for injuries makes additional cover imperative, while it is clear on a weekly basis that this team requires a quality striker to spearhead the team.
Likelihood of business being done: 9/10. While there is always a slight chance that events conspire against your team and no business is done, it seems implausible that Everton will not add to the squad this window. As for outgoings, Everton should look to trim down an overcrowded midfield.
Pick a target: Olivier Giroud was linked throughout the summer, and Koeman thought he had his man at one stage before the player opted to stay at Arsenal. It remains to be seen if Everton revisit their pursuit this time around, but it is likely Sam Allardyce will be looking at strikers of that ilk.
Predict a move: Continually linked with a move throughout his time at the club, it is rather surprising that Kevin Mirallas has lasted this long at Everton. But with the winger starting just two league games all season and struggling for consistency these past few seasons, this upcoming transfer window seems the right time for a parting of ways.