Clubs will be on the hunt for a bargain or big-money signing, whether they are aiming for the title, looking to clinch a European spot or trying to avoid relegation.
There is one interesting point to consider this season – players who have played for one team in Europe are no longer cup-tied when they move to another club participating in European competition.
So could that mean clubs are more willing to splash the cash?
How player values are worked out
London-based investment company Carteret Analytics advises three Premier League clubs, and another 12 leading sides from around Europe and the rest of the world, on potential new signings.
Its data centres on the ‘intrinsic value’ of a player – a fee calculated by assessing their performances for the selling club and the projected impact on the buying club, as well as taking into consideration their prime age (usually 26-30).
The company has provided data for some of the names on BBC Sport’s list of players who could move in January
*POGBA (26, midfielder, Manchester United)
Carteret value: £85m
Linked with: Real Madrid, Barcelona, Juventus
The observant ones among football fans will have noticed that Paul Pogba was on BBC Sport’s list of possible movers last January. The midfielder heads the list once again because the transfer chat will just not go away.
The French World Cup winner’s appearances have been limited this season because of an ankle injury but Manchester United manager Ole Gunnar Solskjaer has declared the midfielder “will not be sold”.
Questions remain about his Old Trafford future, though.
*ERIKSEN (27, midfielder, Tottenham)
Linked with: Real Madrid, Manchester United
“Christian Eriksen has fallen out of love with the club.”
That was BBC Radio 5 Live summariser Darren Fletcher’s view when watching the Denmark international earlier this season.
Eriksen failed to secure a move away from Spurs in the summer and Carteret say his performances have dropped by 38.5% this season, leading to a drop in his value of £32.22m. Tottenham manager Jose Mourinho, asked about Eriksen, has said: “I know his future.”
His contract at Spurs ends in the summer and he has shown no inclination to sign a new deal, meaning chairman Daniel Levy may look to recoup some money in January should a decent offer come in.
*GIROUD (33, striker, Chelsea)
Linked with: Inter Milan, Atletico Madrid
Another on the list who is a World Cup winner with France.
Olivier Giroud has fallen out of favour at Chelsea under Frank Lampard, mainly because of the prolific form of England international Tammy Abraham, while Michy Batshuayi is also ahead of him in the pecking order.
The former Arsenal striker’s contract at Stamford Bridge ends in the summer. With almost 80 goals during his Premier League career, he will be an excellent addition for a club lacking a regular scorer.
*BALE (30, winger, Real Madrid)
Linked with: Tottenham, Manchester United
“Wales. Golf. Madrid. In that order.”
Gareth Bale was already under pressure from the Real fans and he hardly endeared himself as he celebrated with a flag displaying the above message as Wales qualified for Euro 2020.
A move to China broke down in the summer and the former Tottenham and Southampton player has been in and out of the team under Zinedine Zidane. Bale, according to his agent, is “not ecstatic” at the club.
*WERNER (23, striker, RB Leipzig)
Linked with: Real Madrid, Manchester United, Chelsea, Liverpool
With champions Bayern Munich and Borussia Dortmund floundering, RB Leipzig have taken charge of the Bundesliga title race.
Striker Timo Werner has played a big role in that run, his 18 goals coming at a rate of one every 79 minutes, and the Germany international could leave if the right offer came in.
*CAVANI (32, striker, Paris St-Germain)
Linked with: Atletico Madrid, LA Galaxy
Uruguay international Edinson Cavani has been pushed down the pecking order at Parc des Princes behind new arrival Mauro Icardi, Kylian Mbappe and – when he is fit – Neymar.
Cavani has scored just three goals this season, his contract is up in June and he could be available at a decent price in January.
*LEMAR (24, winger, Atletico Madrid)
Linked with: Lyon
France international Thomas Lemar was the subject of a £60m bid from Liverpool in 2017, but he stayed at Monaco, and Arsenal failed to sign him in January 2018.
He eventually moved to Atletico Madrid that summer for £52.7m but has been unable to hold down a first-team place. In December, he was booed off by his own fans, despite the team beating Osasuna.
*ZANIOLO (20, midfielder, Roma)
Linked with: Tottenham, Manchester United, PSG
Midfielder Nicolo Zaniolo moved to Roma as part of the deal that took Radja Nainggolan to Inter Milan at the start of the 2018-19 season. It is fair to say Roma got a bargain.
The 20-year-old’s form, which saw him voted Serie A’s best young player in his debut season, has seen him break into the Italy side.
*MURIQI (25, striker, Fenerbahce)
Linked with: Leicester, Tottenham, Eintracht Frankfurt, Monaco
Vedat Muriqi only joined Turkish giants Fenerbahce in the summer but has scored 10 goals for the club and could be on the move again.
The towering Kosovo striker, 25, scored in a Euro 2020 qualifier against England – and a number of Premier League clubs are taking an interest.