Southampton, naturally, have been left frustrated, having had an agreement in place to sign the Belgian on a permanent deal - only to see it canceled by Atletico Madrid in favour of selling to Spurs.
Yet Manchester United may also suffer thanks to the White Hart Lane outfit.
Indeed, Tottenham's capture of Alderweireld won't make things any easier for United when it comes to their pursuit of Morgan Schneiderlin. Manchester United have emerged as favourites for the Tottenham and Arsenal-linked Southampton midfielder, with the Daily Mail reporting that the club's representatives are currently holding talks with the Saints.
But Southampton won't be keen on losing two key players in quick succession, will they?
Schneiderlin has looked like an inevitable departure at St Mary's for some time but that would naturally have gone alongside Alderweireld looking very likely to feature for Southampton next season. Without him, someone who can play in defence as well as defensive midfield, will the Saints be prepared to lose their key midfielder, as well?
It certainly won't make things easier for Manchester United, with Southampton surely likely to demand even more now that they will have to compensate for Alderweireld's move to Spurs.
The Mail claim a £20 million offer has been rejected. But the asking price might have gotten a lot higher thanks to Tottenham. Or no sale at all.