Shelvey trod on the right foot of Alli, who was sitting on the ground, as he tried to resume play after a free kick had been awarded.
Tottenham, meanwhile, start with last season's English Premier League goal king Harry Kane as the lone man and will be backed by former Newcastle captain Moussa Sissoko, Delle Ali and Christian Eriksen.
Kieran Trippier's injury forced perhaps the most intriguing selection on the day, with Tottenham youngster Kyle Walker-Peters earning his first ever start - or any minutes whatsoever - at the senior level.
Eriksen worked Rob Elliot four minutes before half-time with a dipping, 25-yard drive the goalkeeper saw all the way and was able to hold.
If Pochettino needs to change things at St. James' Park, he can turn to Cameron Carter-Vickers, while Victor Wanyama and Heung-Min Son are also amongst the options on the bench.
Not what you want when you've just been promoted to the Premier League.
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.
Shelvey has been sent off twice under Benitez at Newcastle, more than any other player. He was also red carded in a Championship match at Nottingham Forest in December 2016.