The on-loan Borussia Dortmund midfielder will line up alongside Isaac Hayden in the centre of midfield in one of three enforced changes from the team that lost 2-0 to Tottenham Hotspur last weekend.
With Florian Lejeune and Paul Dummett injured, captain Jamaal Lascelles and fellow centre back Chancel Mbemba are back at the heart of the Magpies' defence in front of goalkeeper Rob Elliot, with Javier Manquillo at right back and Ciaran Clark moving across to left back.
Matt Ritchie will start on the right-hand side of midfield, with Merino replacing the suspended Jonjo Shelvey alongside Hayden and left winger Christian Atsu also starting.
And Ayoze Perez will continue to provide support Dwight Gayle in attack.
On the bench, Karl Darlow provides backup for Elliot, while there are also places among the substitutes for Henri Saivet and new arrival Joselu, who could make his debut.
Jacob Murphy, Mohamed Diame, Rolando Aarons and Aleksandar Mitrovic complete the list of players available for manager Rafa Benitez to call upon.
Newcastle United (4-4-1-1): Rob Elliot; Javier Manquillo, Chancel Mbemba, Jamaal Lascelles (c), Ciaran Clark; Matt Ritchie, Mikel Merino, Isaac Hayden, Christian Atsu; Ayoze Perez; Dwight Gayle.
Substitutes: Karl Darlow, Henri Saivet, Mohamed Diame, Jacob Murphy, Rolando Aarons, Joselu, Aleksandar Mitrovic.