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