Novak Djokovic has announced his resignation as head of the ATP's Player Council and intends to form a new breakaway body to represent athletes -- but his plans have immediately met with stiff resistance from within tennis.

World number one Djokovic, Canadian Vasek Pospisil and top-ranked American John Isner all resigned from the council after they were formally requested to step down by other members, a source told Reuters on Saturday.

Djokovic's move to form a separate players association seemed to have brought together the governing bodies, who called for unity at a time when tennis has been ravaged by the COVID-19 pandemic.

The Serb, who beat Canada's Milos Raonic in the final of the Western & Southern Open 1-6 6-3 6-4 in New York on Saturday, was however still determined to push ahead with the breakaway group.

"I have read in the letter from ATP, that they think that ATP cannot co-exist with the association," the 17-times Grand Slam winner said. "I have to respectfully disagree.

"This is not a union. This is a player association."

The ATP governs the men's professional tour and its board, chaired by former Italian professional player Andrea Gaudenzi, is composed of representatives of both players and tournament owners.

"We recognise the challenges that our members face in today's circumstances, however, we strongly believe that now is a time for unity, rather than internal division," an ATP statement said.

"We remain unwavering in our commitment to deliver for our players across all areas of our business, ensuring they receive maximum benefit from their years on Tour, and their voices are heard."

Besides the ATP and the WTA, the sport is also controlled by the International Tennis Federation (ITF) and the boards of the four Grand Slams.

In a joint statement, the governing bodies said they have worked "tirelessly" to ensure the sport returned safely after a five-month hiatus and help the players who needed financial help during the shutdown.

"Now more than ever we need collaboration and strong relationships, and we fully support the ATP in its role in representing the best interests of players throughout this process," it said.

FEDERER, NADAL WEIGH IN

The players are now present in New York's bio-secure bubble ahead of the US Open, which starts on Monday.

Roger Federer and Rafa Nadal, who make up the 'Big Three' of men's tennis along with Djokovic, are also part of the council but have opted out of playing this year's U.S. Open.

Nadal echoed the ATP's thoughts.

"The world is living a difficult and complicated situation. I personally believe these are times to be calm and work all of us together in the same direction," he said on Twitter.

"It is time for unity, not for separation."

Federer, the most successful men's player with 20 Grand Slam singles titles, agreed with Nadal.

"These are uncertain and challenging times, but I believe it's critical for us to stand united as players, and as a sport, to pave the best way forward," said the 39-year-old, who is recovering from double knee surgeries.

Djokovic said he "would love to have Roger and Rafa on board" but that he understood their perspective.

"It's like having a baby. The time is never right or it's always right," said Djokovic.

"We are just trying to get a sense of how many players do really want to join this initiative. Then we will take it from there."