Alderweireld has established himself as one of the Premier League’s best defenders since arriving in England in 2014.
Since joining Spurs in 2015, the Belgian centre-back has formed a formidable relationship with compatriot Jan Vertonghen.
But Alderweireld will be out of contract in 2019 and despite talks over a renewal, no agreement has been reached leading to speculation that a move could be on the cards.
And according to the Manchester Evening News, United are keeping tabs on Alderweireld’s situation.
It is claimed the 28-year-old has the option of a one-year extension in his deal but also a £25million release clause which can be activated in the 2019 summer transfer window.
Jose Mourinho has spent heavily on defenders in recent years with Victor Lindelof and Eric Bailly coming in.
But Chris Smalling and Phil Jones’ futures are in doubt after United lost back-to-back away games with the pair in central defence.
Alderweireld has missed several months with injury but returned to action last month.
However, he will miss Spurs’ Champions League last-16 clash with Juventus tonight.
And manager Mauricio Pochettino insists he is trying to protect Alderweireld’s career by managing his minutes.
“From day one our idea is to create a plan to help him, because that’s the most important thing,” Pochettino said.
“He is 28 and it was a massive injury that we need to care about, because we could not put at risk his career. We designed a plan to try to provide him with the best tools to recover as soon as possible and be stronger than before.
“In that period that he started to work with the team, under our judgement, he needs to build his fitness slowly. He needs to work hard. To play this type of game (against Juventus) you need to be 200 per cent.
“It’s not the same as training to compete, and that’s why we are caring about him with our plan, to try for him in to be at a high level of condition again, (and) can be competing for one place in the starting eleven. That is always what we try to do with different players. Of course we are sorry for him because when you miss some games like Arsenal or the Champions League, and we work a lot to play this type of game, I can understand that (he is frustrated). We are frustrated too because, when you cannot play, it is difficult to accept.
“But I think in front, in his career, is of course a very important game but, sure he is going to have the opportunity and be strong after the injury, but we need to apply our common sense and be careful in the way that we are going to use him in the first few weeks after he is fit for training.
“We were lucky to have the replay against Newport for him to feel the competition. It’s all going well. He will be part of the team to face Rochdale next Sunday and then we are going to assess him day-by-day.”