Manchester United are reportedly closing in on the signing of Napoli defender Kalidou Koulibaly.

The 28-year-old is a long-term target for United and is said to have been made available to purchase for £74m this summer.

Having broke the transfer record to sign Harry Maguire from Leicester City last year, the Red Devils are supposedly eager to further strengthen at the back as Ole Gunnar Solskjaer attempts to puzzle together a title-winning side.

Seeing off competition from Manchester City and Paris Saint-Germain for Koulibaly would be seen as a huge statement of intent, but there is still work to be done to get a deal over the line.

Here, Sports Mole looks at the shirt numbers available for the Senegal international at Old Trafford should he arrive during this summer's transfer window.

Koulibaly wears the number '26' for Napoli and has done since joining the Italian club in 2014.

That shirt is currently owned by Timothy Fosu-Mensah, who has not played for United in the last three years but was recently awarded a new contract.

Former Genk and Metz defender Koulibaly has also previously sported the numbers 'five' and '25' on his back, though both of those are also taken at Old Trafford.

Maguire is in possession of 'five' and is unlikely to give up ownership of that anytime soon, while '25' is Odion Ighalo's, though his loan deal is only due to run until the end of the season.

'Four' is the other number associated with central defenders, and that may soon be freed up should Phil Jones depart the club at the end of the campaign.

The number '12' shirt may also soon become available, meanwhile, given the uncertainty surrounding Chris Smalling's future, while '16' is also up for grabs at this moment in time.

'Eleven', usually worn by attacking players, is the most notable number that is unoccupied, while further down the list '19', '27' and '30' are up for grabs.