Jan Vertonghen is a summer transfer target for Napoli as the Italian club plan to overhaul their defence.

Napoli’s back four has proved their Achilles heel in Serie A this season, and they are keen to make changes at the end of the campaign – irrespective of whether Rafael Benitez remains their manager.

Napoli considered a move for Vertonghen, who is under contract at Tottenham until the summer of 2018, last June, only to decide against making a formal offer.

But sources in Italy have indicated to Standard Sport that the Belgian is back on their radar.

Despite some shaky performances this season, it is believed Spurs have no immediate plans to sell Vertonghen. The 27-year-old has captained the side in certain games during the campaign and has established himself as Mauricio Pochettino’s first-choice centre-back.

And having signed the player for £9million three years ago, Spurs chairman Daniel Levy would seek a substantial profit were he to consider a sale.

Yet there are reasons for Napoli to believe a deal is possible. Vertonghen said last September that he would not be signing a new deal at White Hart Lane, after the club chose to activate an option to extend the contract by two years to 2018.

International break: 10 Premier League transfer targets to watch 9 show all International break: 10 Premier League transfer targets to watch 1/9 Tottenham target Target: Lucas Biglia

Age: 29

Estimated value: £11m

Tottenham target Lucas Biglia is a fine technical player, who is strong in the tackle. The Lazio defensive midfielder has wide passing range but he can be conservative and, given space, will more likely pick out a team-mate than maraud forward with the ball. Biglia can strike the ball well from range and scored a stunning free-kick against Torino earlier this season. He made seven appearances for Argentina at last year's World Cup and is set to feature in the upcoming friendlies.

Where to watch him:

El Salvador v ARGENTINA (Saturday, 8.30pm)

Ecuador v ARGENTINA (Wednesday, 1am) GETTY 2/9 Tottenham target Target: Kevin Wimmer

Age: 22

Estimated value: £6m

Tottenham are close to agreeing a deal to sign Austria international Kevin Wimmer from German club Cologne. Wimmer has helped the Bundesliga newcomers steer clear of relegation, missing just one league match and helping Cologne keep the best defensive record outside the Bundesliga top five. The physical centre-half's eye for a pass can turn defence to attack in an instant. The left-footed Austria international has also been used as a full-back but prefers a central defensive role.

Where to watch him:

Liechtenstein v AUSTRIA (Friday, 7.45pm, Sky Sports Red Button)

AUSTRIA v Bosnia (Tuesday, 7.15pm) GETTY 3/9 Tottenham target Target: Toby Alderweireld

Age: 26

Estimated value: £10m

Southampton loanee Toby Alderweireld has dropped a strong hint that he would like to join Tottenham, telling reporters he wants to play alongside Jan Vertonghen again. Saints have the tightest defence in the Premier League and Alderweireld has helped them keep nine clean sheets in his 18 starts. The versatile, hard-tackling defender usually features at centre-back but has filled in at right-back and in deep midfield this season; he tends to feature at right-back for the Belgium national side.

Where to watch him:

BELGIUM v Cyprus (Saturday, 7.45pm, Sky Sports Red Button)

Israel v BELGIUM Tuesday, 7.45pm, Sky Sports 5) GETTY 4/9 Chelsea target Target: Koke

Age: 23

Estimated value: £48m

Chelsea will use Atletico Madrid's interest in re-signing Filipe Luis this summer to lure the Spanish club's star midfielder Koke. Koke came through Atleti's academy and generally plays on the left side of Diego Simeone's midfield, though he has featured on the opposite flank and through the middle. The 23-year-old - who boasts an excellent set-piece delivery - has provided nine assists in La Liga this season and has excelled in European competition, making an average of 3 key passes per game.

Where to watch him:

SPAIN v Ukraine (Friday, 7.45pm, Sky Sports 5)

Netherlands v SPAIN (Tuesday, 7.45pm) GETTY 5/9 Chelsea target Target: Raphael Varane

Age: 21

Estimated value: £26m

Jose Mourinho will this summer launch an ambitious raid to sign Raphael Varane, who he recently heralded as the best young defender in the world. The centre-back has started 14 La Liga matches for Real Madrid already this term - his most starts in one season since arriving at the Bernabeu in 2011. Varane is strong in the air and composed with the ball at his feet, maintaining a 90% successful pass rate across all competitions this season. He has been a regular starter for the France national side since early 2014.

Where to watch him:

FRANCE v Brazil (Thursday, 8pm)

FRANCE v Denmark (Sunday, 7.45pm) 6/9 Chelsea target Target: Douglas Costa

Age: 24

Estimated value: £17m

Shakhtar Donetsk star Douglas Costa still hopes to complete a switch to Chelsea despite January's failed move to Stamford Bridge. The pacy right-sided winger is full of tricks and has showcased a striker's finish when used through the middle. Costa was called up to the Brazil national team in November 2014 and made two substitute appearances. He said in March: "I am interested in moving to Chelsea – not only because everything Willian tells me about the club, but because I think that I’d be able to achieve everything I want having someone like Jose Mourinho by my side."

Where to watch him:

France v BRAZIL (Thursday, 8pm)

BRAZIL v Chile (Sunday, 3pm, Emirates Stadium) GETTY 7/9 Arsenal target Target: Edinson Cavani

Age: 28

Estimated value: £44million

Edinson Cavani has scored 40 goals in 71 games since joining Ligue 1 champions PSG in July 2013. The Uruguayan international is a quality finisher with his head and both feet and can play across the front three, but he is struggling to convince the Parc des Princes faithful with a league tally of just eight in 22 starts this campaign. Cavani will likely lead the line for Uruguay against Morocco on Saturday after Luis Suarez was granted permission to avoid international duty to feature in Steven Gerrard's testimonial at Anfield. Where to watch him:

Morocco v URUGUAY (Saturday, 8pm) GETTY 8/9 Arsenal target Target: Aleksandar Dragovic

Age: 24

Estimated value: £10m

Former Tottenham player and Dynamo Kiev manager Sergei Rebrov has described Aleksandar Dragovic as 'one of the best players in his team' and warned suitors off him earlier this month amid interest from Arsenal. The centre back can also play in a deep midfield role, but has starred at the heart of Kiev's defence alongside Yevhen Khacheridi and Danilo Silva. Dragovic is composed with the ball at his feet and unlikely to venture from deep, using his eye for a pass to play out from the back. The 24-year-old reads the game well and intervenes with firm tackles and regular interceptions at the back. As such, Kiev have conceded just seven league goals all season.

Where to watch him:

Liechtenstein v AUSTRIA (Friday, 7.45pm, Sky Sports Red Button)

AUSTRIA v Bosnia (Tuesday, 7.15pm) GETTY 9/9 Various suitors Target: Alexandre Lacazette

Age: 23

Estimated value: £18m

Lyon forward Alexandre Lacazette has caught the eye of Liverpool and Arsenal this season after scoring 23 Ligue 1 goals this season. The 23-year-old is excelling behind lead striker Nabil Fekir at Stade Lyon and fired his way back into the France national squad in November after missing the World Cup last summer. The physical forward is composed in and around the opponents' penalty area and complements a smart finishing touch with pinpoint bullets from range. Lacazette is yet to feature in a competitive game for France but will likely get game time in the upcoming friendlies.

Where to watch him:

FRANCE v Brazil (Thursday, 8pm)

FRANCE v Denmark (Sunday, 7.45pm) GETTY 1/9 Tottenham target Target: Lucas Biglia

Age: 29

Estimated value: £11m

Tottenham target Lucas Biglia is a fine technical player, who is strong in the tackle. The Lazio defensive midfielder has wide passing range but he can be conservative and, given space, will more likely pick out a team-mate than maraud forward with the ball. Biglia can strike the ball well from range and scored a stunning free-kick against Torino earlier this season. He made seven appearances for Argentina at last year's World Cup and is set to feature in the upcoming friendlies.

Where to watch him:

El Salvador v ARGENTINA (Saturday, 8.30pm)

Ecuador v ARGENTINA (Wednesday, 1am) GETTY 2/9 Tottenham target Target: Kevin Wimmer

Age: 22

Estimated value: £6m

Tottenham are close to agreeing a deal to sign Austria international Kevin Wimmer from German club Cologne. Wimmer has helped the Bundesliga newcomers steer clear of relegation, missing just one league match and helping Cologne keep the best defensive record outside the Bundesliga top five. The physical centre-half's eye for a pass can turn defence to attack in an instant. The left-footed Austria international has also been used as a full-back but prefers a central defensive role.

Where to watch him:

Liechtenstein v AUSTRIA (Friday, 7.45pm, Sky Sports Red Button)

AUSTRIA v Bosnia (Tuesday, 7.15pm) GETTY 3/9 Tottenham target Target: Toby Alderweireld

Age: 26

Estimated value: £10m

Southampton loanee Toby Alderweireld has dropped a strong hint that he would like to join Tottenham, telling reporters he wants to play alongside Jan Vertonghen again. Saints have the tightest defence in the Premier League and Alderweireld has helped them keep nine clean sheets in his 18 starts. The versatile, hard-tackling defender usually features at centre-back but has filled in at right-back and in deep midfield this season; he tends to feature at right-back for the Belgium national side.

Where to watch him:

BELGIUM v Cyprus (Saturday, 7.45pm, Sky Sports Red Button)

Israel v BELGIUM Tuesday, 7.45pm, Sky Sports 5) GETTY 4/9 Chelsea target Target: Koke

Age: 23

Estimated value: £48m

Chelsea will use Atletico Madrid's interest in re-signing Filipe Luis this summer to lure the Spanish club's star midfielder Koke. Koke came through Atleti's academy and generally plays on the left side of Diego Simeone's midfield, though he has featured on the opposite flank and through the middle. The 23-year-old - who boasts an excellent set-piece delivery - has provided nine assists in La Liga this season and has excelled in European competition, making an average of 3 key passes per game.

Where to watch him:

SPAIN v Ukraine (Friday, 7.45pm, Sky Sports 5)

Netherlands v SPAIN (Tuesday, 7.45pm) GETTY 5/9 Chelsea target Target: Raphael Varane

Age: 21

Estimated value: £26m

Jose Mourinho will this summer launch an ambitious raid to sign Raphael Varane, who he recently heralded as the best young defender in the world. The centre-back has started 14 La Liga matches for Real Madrid already this term - his most starts in one season since arriving at the Bernabeu in 2011. Varane is strong in the air and composed with the ball at his feet, maintaining a 90% successful pass rate across all competitions this season. He has been a regular starter for the France national side since early 2014.

Where to watch him:

FRANCE v Brazil (Thursday, 8pm)

FRANCE v Denmark (Sunday, 7.45pm) 6/9 Chelsea target Target: Douglas Costa

Age: 24

Estimated value: £17m

Shakhtar Donetsk star Douglas Costa still hopes to complete a switch to Chelsea despite January's failed move to Stamford Bridge. The pacy right-sided winger is full of tricks and has showcased a striker's finish when used through the middle. Costa was called up to the Brazil national team in November 2014 and made two substitute appearances. He said in March: "I am interested in moving to Chelsea – not only because everything Willian tells me about the club, but because I think that I’d be able to achieve everything I want having someone like Jose Mourinho by my side."

Where to watch him:

France v BRAZIL (Thursday, 8pm)

BRAZIL v Chile (Sunday, 3pm, Emirates Stadium) GETTY 7/9 Arsenal target Target: Edinson Cavani

Age: 28

Estimated value: £44million

Edinson Cavani has scored 40 goals in 71 games since joining Ligue 1 champions PSG in July 2013. The Uruguayan international is a quality finisher with his head and both feet and can play across the front three, but he is struggling to convince the Parc des Princes faithful with a league tally of just eight in 22 starts this campaign. Cavani will likely lead the line for Uruguay against Morocco on Saturday after Luis Suarez was granted permission to avoid international duty to feature in Steven Gerrard's testimonial at Anfield. Where to watch him:

Morocco v URUGUAY (Saturday, 8pm) GETTY 8/9 Arsenal target Target: Aleksandar Dragovic

Age: 24

Estimated value: £10m

Former Tottenham player and Dynamo Kiev manager Sergei Rebrov has described Aleksandar Dragovic as 'one of the best players in his team' and warned suitors off him earlier this month amid interest from Arsenal. The centre back can also play in a deep midfield role, but has starred at the heart of Kiev's defence alongside Yevhen Khacheridi and Danilo Silva. Dragovic is composed with the ball at his feet and unlikely to venture from deep, using his eye for a pass to play out from the back. The 24-year-old reads the game well and intervenes with firm tackles and regular interceptions at the back. As such, Kiev have conceded just seven league goals all season.

Where to watch him:

Liechtenstein v AUSTRIA (Friday, 7.45pm, Sky Sports Red Button)

AUSTRIA v Bosnia (Tuesday, 7.15pm) GETTY 9/9 Various suitors Target: Alexandre Lacazette

Age: 23

Estimated value: £18m

Lyon forward Alexandre Lacazette has caught the eye of Liverpool and Arsenal this season after scoring 23 Ligue 1 goals this season. The 23-year-old is excelling behind lead striker Nabil Fekir at Stade Lyon and fired his way back into the France national squad in November after missing the World Cup last summer. The physical forward is composed in and around the opponents' penalty area and complements a smart finishing touch with pinpoint bullets from range. Lacazette is yet to feature in a competitive game for France but will likely get game time in the upcoming friendlies.

Where to watch him:

FRANCE v Brazil (Thursday, 8pm)

FRANCE v Denmark (Sunday, 7.45pm) GETTY

At the time, Vertonghen said: “'I am not signing, no. We agreed not to. I would prefer not to say why. I still have four years left. I am happy at the club and I think they are happy with me. That's where it ends.”

Vertonghen has also told friends that he is keen to test himself in Serie A at some stage during his career. Napoli’s interest last summer is thought to have been promoted by winger Dries Mertens, who plays alongside Vertonghen for Belgium.

Vertonghen earns about £40,000 a week at Spurs, which would pose little problem for Napoli. Top earner Gonzalo Higuain collects a weekly wage of £150,000 a week but the majority of the squad come in around the £30,000 mark.