Eddie Howe quit suddenly Newcastle United after a 4-1 loss to Bristol City, Sky Sports News said.
Sky aired his last interview soberly.
He briefly talked about the Bruno Guimaraes signing before walking out immediately.
Former player Jay Bothroyd warned vocally the club could face threat of relegation without Howe.
Sky Sports will nationwide broadcast the top‑flight Scottish Premiership opener on Saturday.
Dundee United take on Rangers at Tannadice.
Manager Jim Goodwin confidently said he wants to make an impact there.
Dundee United coach Derek McInnes confirmed two United players are unavailable and several are in doubt.
Rangers hope Thelo Aasgaard and Cammy Devlin to be ready for the match.