The Chelsea boss issued the warning just after Manchester United rejected a bid from the Blues for 27-year-old Wayne Rooney, who has been told by new manager David Moyes that Robin van Persie is the club’s first-choice striker.
“Normally for a player to be selected to play for his country, the player must be a first choice player in the club,” Mourinho told reporters in Malaysia during Chelsea’s brand-boosting tour in Asia.
“So any player that wants to go to the World Cup... if they are second choice in their club they are in trouble. They are in trouble,” he warned.
A Chelsea official told reporters before the press conference that 50-year-old Mourinho would not answer any questions related to a failed bid for Rooney.
The England forward has two years left on his contract with Manchester United but has been pushing for a move. Van Persie is seen as United’s first choice striker.
Mourinho has previously stated that striker Rooney was Chelsea's only remaining summer transfer target for the club.