The Premier League transfer window is open, with clubs in the English top flight set to flex their financial muscles.

AFP Sport looks at where the major teams will look to strengthen in January.

Liverpool's rebuild is ahead of schedule after the club signed four new midfielders in the summer transfer window.

Yet it is that area of the pitch where they could look to invest again to try and land just a second league title since 1990.

Wataru Endo has proved a useful stopgap signing after Chelsea won the chase for Moises Caicedo, who joined the London club for a British transfer record.

But Jurgen Klopp's men could still do with a specialist defensive midfielder and Fulham's Joao Palhinha fits the bill.

Palhinha's proposed move to Bayern Munich collapsed at the end of the summer transfer window and the Portugal international has again been one of the Premier League's best in that position this season.

Many doubt whether Aston Villa will last the course and if they have the strength to win their first league title since 1981.

Unai Emery's men have balanced a stunning start in the Premier League with their first European campaign for 13 years.

But their squad could be stretched in the final months of the season should they go far in the Europa Conference League.

Ollie Watkins has been central to Villa's transformation under Emery, but another option up front to take some of the load off the England international is top of their priority list.

The defending champions are not expected to splash out this month as they instead hope for a boost from returning stars.

Attacking midfielder Kevin De Bruyne is nearing a return after a five-month layoff due to a hamstring injury.

Star forward Erling Haaland has missed the past seven games in all competitions due to a foot injury and should be fit after the mid-season player break, during which there are fewer fixtures.

Arsenal's need for a goalscorer is arguably the greatest among the title contenders.

The Gunners' challenge has come off the rails in recent weeks, with shock defeats to West Ham and Fulham.

Bukayo Saka is Arsenal's top scorer, with just six Premier League goals, while strikers Gabriel Jesus and Eddie Nketiah have combined for just eight between them.

Brentford's Ivan Toney has been linked with a move to the Emirates, but is only just approaching a return to action after an eight-month ban for breaching betting rules.

Spurs are set to be the most active of the top five in the transfer market as they respond to an injury crisis and the loss of key players to both the Asian Cup and Africa Cup of Nations.

Cristian Romero is sidelined for a number of weeks while fellow centre-back Micky van de Ven, now back in training, has been out of action since early November.

Genoa defender Radu Dragusin is top of Tottenham's wishlist, with reports suggesting a potential £25 million ($32 million) deal.

Midfield reinforcements are also needed in north London, with Pape Matar Sarr and Yves Bissouma headed to Ivory Coast for the AFCON.

Chelsea's Conor Gallagher is a rumoured target for a switch across the capital.

Spurs did not sign a replacement for the departed Harry Kane and will be without more firepower when captain Son Heung-min leaves to lead South Korea's Asian Cup challenge.

Only Burnley and Sheffield United have scored fewer goals than United's paltry total of 22 in the Premier League.

Competition for Rasmus Hojlund up front is a necessity if Erik ten Hag's men are to mount a challenge for the top four.

More scoring options from the wide areas are also badly needed, with Marcus Rashford stuck on three Premier League goals and Antony on a 30-game scoreless streak.

The Magpies' lengthy injury list has contributed to a miserable run of seven defeats in eight games in all competitions.

Eddie Howe is beginning to get key players back, but the rest of his squad has been left exhausted by a gruelling December schedule.

More strength in depth in midfield is a priority, with Manchester City's Kalvin Phillips tipped for a move to Tyneside.

Despite spending more than £1 billion on new players in three transfer windows, Chelsea boss Mauricio Pochettino has hinted that he needs to dip into the market once more for a proven goalscorer.

The Blues have consistently failed to make the most of their chances this season with Nicolas Jackson's finishing erratic, while Mykhailo Mudryk, Raheem Sterling and Noni Madueke have only sparkled sporadically.

However, Chelsea's desire to spend again could be hampered by a need to meet financial fair play rules, which could lead to major sales this month.