Spurs are two points behind surprise leaders Leicester after a 2-1 Premier League victory over title rivals Manchester City at the Etihad Stadium on Sunday afternoon.
Tottenham are going strong in the Europa League and the north Londoners face Fiorentina on Thursday night in the first leg of their Europa League last-32 tie.
Spurs will have two days to recover before Mauricio Pochettino’s side host Crystal Palace in the FA Cup fifth round at White Hart Lane.
Speaking to Sky Sports, Merson insisted that it would be near impossible for Tottenham to win the Premier League if Pochettino continues to field full-strength teams in all three competitions.
“If Tottenham go for all the competitions, it would be impossible,” Merson told Sky Sports.
“It would be as big a shock if Tottenham win the Europa League and the Premier League as it would be if Leicester City win the Premier League.”
Enhanced odds: Get 8/1 enhanced odds on Tottenham to beat Fiorentina
Tottenham have won their last five Premier League games thanks to victories over Sunderland, Norwich City, Crystal Palace, Watford and Manuel Pellegrini’s City side.
MORE: Latest Man Utd news
MORE: Latest Arsenal news
MORE: The latest football news