The Magpies are currently rooted to the foot of the table having taken just six points from their opening 13 matches.
Their last outing saw them slump to a 2-0 defeat at the hands of Arsenal in Saturday’s early kick-off, but the Toon Army now face two matches in four days against teams directly above them – the Canaries and Burnley.
For their part, Dean Smith's men are on an unbeaten run of three matches, including a spirited 0-0 draw against high-flying Wolves over the weekend.
But Merson believes that Eddie Howe’s side can draw level on points with their much-improved visitors with a win at St. James’ Park.
Speaking to Sportskeeda, he said: “This is a massive game for both teams. Norwich have turned the corner a little bit with two good results in the Premier League. They did well against Wolves and probably could’ve beaten them. Norwich have now put themselves in a position where they can afford to just draw this game.
“Newcastle went gung-ho against Brentford but conceded three goals. They sat back against Arsenal and kept it tight – fair play to them. When they have to go win a game, however, I’m not sure they’re good enough to keep a clean sheet.
“I can’t emphasise how massive the next four days are for Newcastle. If they don’t win their next two games, they probably will be relegated by the end of the season. They haven’t played a cup final in god knows how long – this is a cup final. It’s an absolute must-win game of the highest order. They’re already six points adrift, and they have to win these two games.
“If Norwich are brave, I think they can get something out of this. I think Norwich are going to sit back and let the hosts play, and that could play into Newcastle’s hands this week.”
Merson has predicted a 2-0 Newcastle win.