The Canaries travelled to the Hawthorns on Saturday looking to turn around a desperately poor run of form.
They had gone 11 games without a win in a slide that had left them dangerously close to the relegation zone.
That changed with the win over the Baggies as they managed to move three points clear of the bottom three courtesy of Robbie Brady’s solitary goal.
And Merson says that result has ramped up the already huge pressure surrounding the Tyne-Wear derby as a loss could doom Newcastle.
“It makes Newcastle vs Sunderland very important, if Newcastle lose that at home, that really does put the cat among the pigeons,” he told Soccer Saturday.
“If they get beat on Sunday, and then Norwich go and beat them, that’s it, they’re finished.”
“We talked about how big the game was but it’s gotten bigger. Even for Sunderland, they’re looking thinking ‘if we draw, and Newcastle get beat by Norwich, we’re in trouble’.”
The Magpies though, will be hoping that they can enjoy the fabled new manager bounce in Rafa Benitez’s first home game.
The Spaniard replaced Steve McClaren eight days ago and while he lost to Leicester City in his first game, there was some evidence that things could be changing for the better.
And a win over Sunderland would certainly go a long way to ensuring they avoid relegation again this season.