The Tottenham Hotspur defender has been touted as a prime target for United boss José Mourinho over the past few months.
Spurs value the former Ajax Amsterdam and Atlético Madrid man at around £75 million which is a figure United are not willing to meet.
And now Mourinho has seen someone else get Alderweireld to sign up first - a female fan who wanted to get his signature tattooed on her back.
A supporter had recently declared her intention to ink Alderweireld's autograph onto her skin and, upon seeing that, the Belgium international appealed to his Twitter followers to track her down and make it a reality.
After finally finding the mystery fan, Alderweireld arranged to meet her at a tattoo parlour where he happily signed his autograph for the artist to trace on to her back.
A few weeks ago, this girl reached out to me saying she wanted my autograph as a tattoo. Thanks to my followers we found her and we made it happen! ✒😉 pic.twitter.com/YBzre4I3qA— Alderweireld Toby (@AlderweireldTob) August 5, 2018
Now Mourinho is hoping the next time Alderweireld scrawls his signature it will be on a contract securing his move to Old Trafford.
Alderweireld struggled to secure first team football at Spurs last season as Mauricio Pochettino turned to Jan Vertonghen and Dávinson Sánchez as his preferred centre-back partnership, with several reports claiming that a contract dispute played a role in his omission from the team.
The 29-year-old has just one year left on his contract with the club and though he has an optional one-year extension, that would trigger a release clause of just £25 million in the final weeks of the 2019 summer window.