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