Manchester United are on red alert after Barcelona warned Matthijs de Ligt they will not change their contract offer.
Ajax captain De Ligt has been linked with a host of top European clubs after emerging as the hottest property in world football.
Barcelona have been leading the race for his signature for some time, while United, Bayern Munich and Juventus all credited with an interest.
De Ligt's agent Mino Raiola is said to have held further discussions with the La Liga winners after initial talks in April, but wants improved terms following Ajax's run to the Champions League final.
SPORT deny Raiola is proving to be a stumbling block in negotiations and insist he just wants the best deal for his client, with better money on elsewhere.
It is claimed De Ligt is tempted by the proposals, with some clubs offering almost double the terms on the table from Barca.
That has blown the transfer wide open with Barca chiefs privately admitting they may made a mistake by not agreeing a deal, as they did with Frenkie de Jong.
Barca remain confident the opportunity to play for the club will trump any financial deal.
The La Liga champions still expect De Ligt to put pen-to-paper but have warned him they will not change their stance and pay an extortionate salary.
Manchester United remain in the hunt for De Ligt, despite their failure to secure Champions League football for next term.
That is not believed to have put the teenage defender off making the switch, with Ole Gunnar Solskjaer desperate for defensive reinforcements.
Liverpool had also been credited with an interest but they are likely to stick with their current defensive options.
