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