Wilfried Zaha's exit from Crystal Palace this summer has been thrown in doubt as chairman Steve Parish issued a firm warning over his prized asset.
The 28-year-old wants to leave Selhurst Park during the transfer window as he wants a new challenge.
Zaha, who has two years left on his current deal, has been previously linked with a move to Arsenal and Tottenham, but Palace have been able to fend off interest for the winger.
Manchester United are in line for a windfall if he departs the Eagles as they inserted a 25% sell-on fee when he left Old Trafford to join Palace, according to Manchester Evening News.
Palace have previously valued him around the £40million mark and if that's the type of money he goes for, United could receive up to £10m.
What's an acceptable price for Wilfried Zaha? Comment below
But Palace aren't willing to let him go on the cheap as chairman Parish insists the offer needs to be right for the club as well.
Parish told BBC Sport : "We understand his position. "It's no secret that he would like to challenge himself.
"But it has to be right for the football club. He understands that as well.
"If those two things collide then we will have to look at it. But right now, we are two days into the transfer window so it's a bit early to talk about it."
United originally bought Zaha from the South London club in 2013 for £10.58m but he struggled to make an impact in Manchester and after loan spells at Cardiff and Palace, he was sold back to the club in 2015 for £6m.
The Red Devils put the clause in the deal which Palace would later ask them to waive in talks over the signing of Aaron Wan-Bissaka in 2019.
United stuck to their guns, however, and are now in line for a cash boost if Zaha seals his exit this summer or next.
The winger was instrumental for Palace once again this season with 11 goals in 30 games in the Premier League.
