Matthijs de Ligt has not travelled with the Bayern Munich squad to South Korea, as a potential move to Man United beckons.
The German giants have named their group to take part in their Audi summer tour this summer and the Dutchman is a notable omission.
Erik ten Hag is keen to be reunited with his former Ajax captain De Ligt and publicly declared United's interest in the centre-back earlier this month.
United have already strengthened at the back with the £52million addition of Leny Yoro - who suffered an injury in preseason - from Lille, but De Ligt remains on their radar.
His omission from Vincent Kompany's squad suggests work behind the scenes is accelerating and Jan Aage Fjortoft claims the defender is 'waiting for a solution' with Man United.
Matthijs de Ligt was a notable omission from Bayern Munich's touring squad
Bild reported that United had a bid of £30m rejected last week but the Old Trafford club could return with an improved offer.
Speaking in an interview with Dutch media outlet AD, Ten Hag said: 'It remains to be seen whether Matthijs de Ligt will come, I know him well.
'I wanted to sign him two years ago but at that time, he was already very far along to join Bayern. Believe it or not, his name did not come from me in the process.
'During my vacation I was three or four weeks out of the process. During that period it was really the club, the newly equipped scouting and recruitment department, that brought in these players.
'The fact that there are also Dutch people among them is in fact a coincidence. Primarily, these were players who were proposed from our organisation. But of course I support it, let that be clear. And we still make the choice together.'
Bayern president Uli Hoeness also previously confirmed the defender could leave this summer, saying: 'It is possible that a defender will still leave.
'De Ligt is Dutch, the coach at Man United is Dutch. I would have no problem if he stays,' he told German journalist Maximilian Koch.
Since arriving in 2022, Ten Hag has spent nearly £500m on transfers during his tenure, signing the likes of Lisandro Martinez, Rasmus Hojlund, and Andre Onana, during his first two seasons in Manchester.
This summer, Joshua Zirkzee and Yoro have been the main additions with Noussair Mazraoui expected to follow soon.
The spending surge is likely to be offset by departures and United are open to selling a large number of players in the squad to balance the books.