The Chelsea manager has come under mounting pressure for a title defence that sees them sit precariously in fourth place in the Premier League table.
The Blues have a tricky run of fixtures coming up which includes a two-legged Champions League clash with Barcelona.
The European competition sandwiches two matches against Manchester United and Manchester City.
And Merson thinks if Chelsea lose those two and exit the Champions League then he will be axed before the west London outfit travel to Burnley on March 17.
“They have got big games coming up now,” Merson told Sky Sports’ The Debate.
“They have got West Brom at home and then they have got the FA Cup, then Barcelona and the two Manchester teams.
“Then it is Palace and then Barcelona.
“If they don’t win the two Manchester games and they don’t go through against Barcelona then I would be surprised if he is there at the next league game after the Barcelona second leg.”
However, despite losing to Bournemouth and Watford in their last two outings, Merson does not believe Chelsea are having a bad season.
“It’s weird but that’s how it works at Chelsea – two years, give your best, win the league, we’ll move on and then go again,” Merson added.
“Man City have blown everybody else apart.
“If Man City were on the same points as Man Utd the top five would be separated by five points and it would be the best league you’ve ever seen in your life.
“This would not be a bad title defence if Man City weren’t unbelievably good.
“There’s no way Chelsea could have matched that.”