Borussia Dortmund may have already signed the 25-year-old's replacement, giving United every reason to go all out for their man.
It's not often the key centre back in a recent World Cup winning side becomes available, but it is now looking more and more likely Borussia Dortmund are preparing for life without star man Mats Hummels.
On Thursday the Bundesliga giants signed young German central defender Matthias Ginter from Freiburg, a hugely promising 20-year-old that has interested several Premier League outfits himself over the last season or so, and himself a member of Germany's successful World Cup squad.
He looks a snip at the reported €10 million euro price, but the move could have huge ramifications as to the availability of giant Dortmund star Hummels, who has been a massive part of the club's return to prominence over the last five years.
He has been constantly linked with both Manchester United and Barcelona in recent months, but a transfer always looked unlikely given Dortmund's loss of talismanic forward Robert Lewandowski to rivals Bayern Munich ahead of the new season.
Surely they wouldn't let both the offensive and defensive stars leave?
Well they might now. Ginter's arrival should mean Jurgen Klopp is a little more open to letting the 25-year-old go, especially if they can bring in a large fee for him.
With Barcelona having recently broken their transfer record bringing Luis Suarez to Catalonia, they may struggle to stump up the £30-40 million Hummels would command.
However, United, with central defence a key area to strengthen and themselves flush with cash committed to restrengthening the side under new boss Louis van Gaal, someone said to be a fan of Hummels, may step in and make what could turn out to be their biggest, and most important signing of the summer.