United have been tracking Virgil van Dijk for months, but the draw of the Champions League was sure to keep him at Parkhead.
But things have changed, and Newcastle could be set to offer £6m for the central defender ... although Celtic want £8m.
Celtic's Champions Leagues hopes were demolished by Legia Warsaw as the Polish side won 2-0 with plenty to spare in the second leg of their third qualifier at the BT Murrayfield stadium.
Trailing 4-1 from the first game in the Pepsi Arena last week, a difficult task for the Hoops became impossible when Michal Zyro notched in the 36th minute to quell any notions of a famous fightback.
The Scottish champions were booed off at the interval and when Michal Kucharczyk added a second on the hour mark the atmosphere threatened to turn ugly for a while with the home side and fans ultimately happy to escape without further punishment.
This crucial tie was Ronny Deila's first big test as Parkhead boss since taking over from Neil Lennon and he came up well short.
Celtic drop into the Europa League play-off which is unlikely to stimulate their fans and while the loss of Champions League money - £20million is a familiar figure - will not debilitate the Parkhead club, there may be ramifications.
Few will be surprised if keeper Fraser Forster leaves for pastures new but others such as defenders Virgil van Dijk and Adam Matthews may feel the time is now right to move on.