The means Atsu will not be able to play again for the Magpies until February at the earliest.
Manager Steve Bruce has confirmed he will look to find a new club for the winger in January transfer window as his contract with the Magpies expire at the end of the season.
Henri Saivet, Achraf Lazaar and Rolando Aarons were also left of the squad.
"Selecting the squad is always difficult because you know you have to leave people out," Bruce told Newcastle's official website.
"With all the players, they're professionals and they want to play week in, week out.
"With the players we've brought in, it makes it even tougher but it's a decision you have to make.
"Those who aren't involved will continue to train and keep themselves right and once we hit December and January, we hope we can get them fixed up with clubs."
Atsu came close to leaving the club during the summer transfer but none of the linked moves materialised.
The Ghana star has played only once this season for Newcastle in the EFL Cup. Read Full Story