After Jose Mourinho expressed his frustration with Manchester United's transfer business so far in this window, the club could now break the world record transfer fee for a defender.

Click through the gallery above to see the five most expensive defenders in football history.

Time is running out for the Portuguese tactician and his vice chairman Ed Woodward, with the Premier League window closing in less than two weeks.

The United boss recently revealed that he gave the club a list of five targets to pursue, and has stated previously that he would ideally like to sign two more players.

However, Woodward has found it difficult to lure Mourinho's desired targets to Old Trafford, after Gareth Bale and Ivan Perisic reportedly opted to stay at their respective clubs.

The Daily Star has now reported that the Red Devils' focus has shifted to England defender Harry Maguire, who impressed during the 2018 FIFA World Cup. However, his exploits in Russia have seen his value skyrocket, and Leicester City are understood to be keen to keep him at the club.

After losing Riyad Mahrez to Manchester City, the Foxes are in no need to sell Maguire, and are believed to want to offer the 25-year-old a new contract.

Read: Mourinho: I Handed The Club A Five-Man Shortlist For Transfers

If Maguire himself asks the club to let him leave, they would apparently only consider selling him for a fee of £80 million (R1.39 billion), which is more than what Liverpool paid Southampton for Virgil van Dijk in January to make him the most world's expensive defender.

Do you think Maguire is worth £80 million? Have your say in the comments section below.