Manchester United have been dealt a blow in their pursuit of Ajax centre-back Lisandro Martinez, according to reports.
The Argentina international has emerged as one of United's top transfer targets this summer.
Erik ten Hag worked with Martinez at the Johan Cruyff Arena for three years and is keen to be reunited with him in Manchester.
Martinez would provide competition for Raphael Varane and Harry Maguire at centre-half, while he can also play as a holding midfielder.
United had hoped to strike a deal with Ajax before they began their tour of Thailand and Australia, but that was not possible.
And the whole move has now been plunged into doubt after Ajax raised their asking price.
The Dutch publication De Telegraaf reports that the Eredivisie champions are now demanding £52m to part with the 24-year-old, who is under contract in Amsterdam until the summer of 2025.
United's latest offer was worth £43m, but Ajax were disappointed that the bid included around £5m in add-ons.
Ten Hag's former club want to receive all the money up front, and United's latest offer was duly rejected for being too low.
The Red Devils must now return to the drawing board less than a month before the Premier League season begins.
Ten Hag may opt to turn his attention elsewhere, or he could try and persuade his superiors at Old Trafford to meet Ajax's demands.
The Dutch giants will be increasingly loath to sell the defender the closer it gets to the start of the new campaign.
United have only completed one signing so far this summer, with Tyrell Malacia joining the club from Feyenoord for £13m.
A deal for Christian Eriksen is expected to go through once the Denmark international passes his medical, but the pursuit of Frenkie de Jong continues to drag on.
United will begin the 2022/23 season against Brighton at Old Traffrd.
