In contrast, Spurs boss Mauricio Pochettino left Tyneside having seen a satisfactory performance from his men, who were eventually rewarded for their patience.
The England global was involved in Tottenham's second as his flick was guided into the path of Davies by Eriksen, the left-back finishing a slick move with a cool finish.
Shelvey caught the England international's right ankle with his left boot in the second half
Newcastle's cause wasn't helped by losing defenders Paul Dummett and Florian Lejeune - the 200th French player to feature in a Premier League game - to injury in the first half.
Atsu, who joined the Magpies permanently from Chelsea in the summer transfer window after impressing on loan last term, has been trusted by manager Rafa Benitez with a starting berth in their first game of the Premier League.
And to nobody's surprise - except Shelvey's - Mariner brandished a straight red card.
Tottenham team to play Newcastle United: Lloris, Walker-Peters, Alderweireld, Vertonghen, Davies, Dier, Dembele, Sissoko, Eriksen, Ali, Kane.