Coutinho, Luiz, Mahrez and Barkley could be high-profile departures in January transfer window

The European winter transfer window opens on Monday, meaning clubs can bolster their squads as they gear up for the final half of the 2017/18 season.

Liverpool have raised the bar before it has even opened. On Wednesday Jurgen Klopp's side agreed a world-record fee for a defender after finalising their long-held interest in Southampton's Virgil van Dijk. The Dutchman's £75 million (Dh369.6m) fee is 50 per cent more than the next most costliest defender in history.

We take a look at other high-profiled players who may be on the move when the January sales begin.

Philippe Coutinho (Liverpool)

The Brazilian was the No 1 target of Spanish giants Barcelona in the summer after the Catalans looked to fill the void left by Coutinho's compatriot Neymar's move to Paris Saint-Germain for a world-record fee. Barca had at least three bids rejected by Liverpool for Coutinho in the summer. The player tried to pave the way for the clubs to negotiate by handing in a transfer request, but Liverpool rejected it, stood firm and have been rewarded for their resistance with some eye-catching performances by the playmaker of late, with four goals in December alone.

Barca have coped without Coutinho in their ranks, currently top of the Primera Liga and through to the knockout stages of the Uefa Champions League. But only a fool would think Ernesto Valverde's team are not primed to test Liverpool's resolve again. The Anfield club have a habit of persuading their want-away stars (think Luis Suarez) to give them one more season before allowing them to move in the summer, so even if Coutinho does not move in this transfer window he almost certainly will the next.

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Read more:

• Richard Jolly: If Van Dijk is tasked with being flawless, Liverpool have got the perfect addition
• Premier League predictions: Chelsea thrash Stoke, Man City make it 19 wins in a row

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David Luiz (Chelsea)

Plenty of heads were turned when Antonio Conte brought David Luiz back from Paris Saint-Germain, but the affable Brazilian was a stalwart of last season's Premier League title-winning team. Recognising a lack of discipline to operate as a holding midfielder, Conte identified Luiz's ability to mop up as the last man in a back three as well as confidently bring the ball out to set up attacks as potent weapons.

Luiz has been largely marginalised this term though since falling out with Conte during a Champions League defeat to Roma and has not played a single Premier League minute since the victory over Manchester United on November 5. The official line peddled by Chelsea is that Luiz is carrying a knee injury, but it seems his questioning of the Italian's tactics, along with the emergence of Andreas Christensen as a front-line defender, could mean he has played his last game at Stamford Bridge.

Seeing Luiz play in anything other than the blue of Chelsea in the Premier League is hard to imagine, but he will need to be playing regularly to convince national team manager Tite he should partner Thiago Silva at the heart of the Brazilian defence at next summer's World Cup in Russia. Reports in Spain have credited Real Madrid with an interest, though Luiz would be ineligible to play in the Champions League having already appeared in it this term for Chelsea. A move back to Portugal with Benfica could be on the cards.

Daley Blind (Manchester United)

Daley Blind's season has been a mixed bag. After starting the first three league games, the Dutchman has played only four additional minutes in the Premier League since. In contrast, he has played every minute of United's Champions League campaign.

Able to operate at left-back, centre-back and in central midfield Jose Mourinho seems to value the Netherlands international's versatility and tactical nous for important European games more than domestic assignments. With players returning from injury, and Luke Shaw seemingly back in favour at left-back under Mourinho, Blind's avenues back to the first team, at least domestically, seem blocked at every turn.

It is unlikely Mourinho would want to lose such an experienced member of his squad, but the former Ajax player is too good to warm the bench. Blind, 27, will have plenty of suitors, with Bayern Munich reportedly keen to explore his availability.

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Read more from the 12th Dubai International Sports Conference:

• Francesco Totti on Mohamed Salah: 'I consider him one of the best players around the world'
• Carles Puyol says spiraling transfer fees in football 'crazy' but 'that's the way football is going now'

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Riyad Mahrez (Leicester City)

The Algerian winger is back to his twinkle-toed best following an alarming dip after helping Leicester win the most improbable of titles in 2016. Mahrez has been directly involved in 17 league goals for the Foxes (seven goals, 10 assists) with his trademark trickery, long-range strikes and ability to feed Jamie Vardy propelling Leicester up the table under new manager Claude Puel.

Mahrez handed in a transfer request in the summer and it remains to be seen whether he sees his long-term future at the King Power Stadium. His attacking talents should appeal to a number of suitors, not least Arsenal's Arsene Wenger, who himself knows he is likely to lose one of, if not both, Mesut Ozil and Alexis Sanchez either this transfer window or in the summer. The Frenchman would do well to bolster his ranks now.

Ross Barkley (Everton)

The midfielder has yet to make an appearance this season because of injury problems. An acrimonious fallout with previous manager Ronald Koeman, as well as a reluctance to agree fresh terms - his current deal expires in 2018 - seemed to signal the end of Barkley's time at Goodison Park. But could that all change under a new man?

Sam Allardyce has expressed a desire to keep the England international, but with only six months remaining on the 24-year-old playmaker's contract a serious offer could see club and player part ways. Barkley has been heavily courted by Chelsea and Tottenham Hotspur in the past and has cited his desire to play Champions League football as a reason for wanting to leave. But whether either of the London clubs still see him as part of their plans remains to be seen. Southampton have cash to burn following Virgil van Dijk's record £75 million transfer to Liverpool, while West Ham United and Newcastle United may also offer him a way out of Goodison.