Steve McClaren was sacked by telephone after choosing not to attend a face-to-face meeting.
McClaren was today relieved of his duties as the relegation-threatened club's head coach by managing director Lee Charnley.
The 54-year-old had been on a day off and opted against meeting Charnley in person, according to Sky Sports News.
Charnley is set to meet potential successor Rafa Benitez for talks on Tyneside this afternoon.
Meanwhile, Newcastle's players have reportedly been asked to report to the training ground for a team meeting.
Like McClaren, they had also been on a day off.
Benitez could be appointed in time to take charge of the team for Monday night's game at Leicester City.