Novak Djokovic has warned that club tennis is “endangered” by a rise in the popularity of padel.

Padel, a hybrid between squash and tennis, is one of the fastest-growing sports, with an estimated 30 million players worldwide, including Lionel Messi, David Beckham and Serena Williams.

Djokovic, 37, said he feared grassroots tennis was at risk of being displaced by padel and pickleball, its American variant which uses thinner rackets and can be played in both singles and doubles.

The seven-time Wimbledon champion, speaking after beating Alexei Popyrin of Australia on Saturday, said tennis had done a “very poor job” in making the sport affordable and accessible for aspiring competitors.

He said: “Tennis is the king or queen of all the racket sports, that’s true. But on a club level, tennis is endangered.