Walker struck from long range early in the second half to get City back to winning ways, though, a week after dropping points for the first time this season.
Relive how the 90 minutes of action unfolded with Sports Mole's live text coverage below.
STARTING XI: Ederson; Walker, Stones, Laporte, Mendy;Fernandinho; Mahrez, D.Silva, Sterling; Jesus, Aguero
SUBS: Muric, Kompany, Gundogan, Delph, Bernardo, Otamendi, Foden
STARTING XI: Dubravka; Yedlin, Clark, Fernandes, Lascelles, Dummett; Diame, Ki, Kenedy, Perez; Rondon
SUBS: Darlow, Sterry, Atsu, Longstaff, Murphy, Muto, Joselu
Pep Guardiola: "Rafa Benitez did the same against us last season, so we have to adapt. Obviously the quality of our play will be important. After two minutes, I will know what idea our opponents are using, and we have to train hard to adapt to it. Last year, when we dropped points we recovered well and that is why we had a good season."
Rafael Benitez: "In all my life as a player and a coach, every year you have two or three situations in the dressing room during a game, or during a training session, when something happens between players. Why? Because they want to win, they care. You want competitive professionals - we have competitive professionals and I think it's very positive."
MANCHESTER CITY SUBS: Muric, Kompany, Gundogan, Delph, Bernardo, Otamendi, Foden
NEWCASTLE UNITED SUBS: Darlow, Sterry, Atsu, Longstaff, Murphy, Muto, Joselu