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 risk 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 plant a flag there.
Dundee United coach Derek McInnes announced two United players are missing and several are questionable.
Rangers hope Thelo Aasgaard and Cammy Devlin to be ready for the match.