The Red Devils have made the England international their top target.
Despite weeks of speculation a move is yet to get over the line, though.
An £80m transfer has been mooted which would make him the most expensive defender of all time.
But according to The Telegraph, Ed Woodward is determined to get more clarity in the coming days.
“Harry Maguire is wanted by Man Utd”
It’s suggested the tight timeframe is being caused by Tottenham man Toby Alderweireld.
The experienced centre-back is United’s Plan B and he has a key clause in his current contract.
It states that the north Londoners must green light his departure if a club lodges a £25m bid by Thursday, as that is two weeks before the window shuts.
Once that clause expires, it is said Spurs supremo Daniel Levy will then demand at least £40m to sell.
Former Wales striker turned pundit Dean Saunders reckons United have missed a trick by not raiding Spurs for Alderweireld earlier.
“It’s got ridiculous now, hasn’t it? £80m for Harry Maguire,” Saunders ranted on talkSPORT.
“It’s not his fault, but where is it going to stop?
“Would you take Toby Alderweireld for £25m or Harry Maguire for £80m?
“You can’t get your money back on Alderweireld, he’s 30, but he’s probably a better player right now.
“As a striker, I’d be thinking to myself, ‘If I can get Maguire out in the channels and get him isolated, he’s not mobile’.”
Alderweireld hinted earlier this week that he’s ready to remain in north London.
“Yes, the release clause is running out and again anything can happen,” said Alderweireld. “But my focus is on Spurs and in my head I will be playing for Spurs.
“My focus is on Spurs and I try to deliver the job I need to do – I’m happy and that’s it.
“Do I think I will still be a Spurs player come the start of the season? Yes – that’s my focus. In football everything can go quickly, but all I’m doing is focusing on Spurs and being fit for the start of the season.”