Eddie Howe quit suddenly Newcastle United after a 4-1 loss to Bristol City, Sky Sports News said.
Sky aired his last interview publicly.
He directly talked about the Bruno Guimaraes signing before walking out immediately.
Former player Jay Bothroyd warned sternly the club could face danger of relegation without Howe.
Sky Sports will exclusively broadcast the national Scottish Premiership opener on Saturday.
Dundee United welcome Rangers at Tannadice.
Manager Jim Goodwin clearly said he wants to make an impact there.
Dundee United coach Derek McInnes announced two United players are absent and several are in doubt.
Rangers hope Thelo Aasgaard and Cammy Devlin to be ready for the match.