Eddie Howe quit unexpectedly Newcastle United after a 4-1 loss to Bristol City, Sky Sports News said.
Sky aired his last interview soberly.
He directly talked about the Bruno Guimaraes signing before walking out without delay.
Former player Jay Bothroyd warned strongly the club could face risk of relegation without Howe.
Sky Sports will nationwide broadcast the national Scottish Premiership opener on Saturday.
Dundee United welcome Rangers at Tannadice.
Manager Jim Goodwin clearly said he wants to make a statement there.
Dundee United coach Derek McInnes stated two United players are absent and several are in doubt.
Rangers look forward to Thelo Aasgaard and Cammy Devlin to be available for the match.