The Serbian star warmed up for the US Open by securing his 80th career title, with a three-set win over Canadian Milos Raonic at the Western and Southern Open in New York on Sunday (NZ time).
The victory came just prior to the confirmed formation of a breakaway players association, which Djokovic has been a driving force in establishing.
The 17-time Grand Slam winner, along with 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 said.
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.
He 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.