The uncapped 23-year-old was dropped by the A-League basement dwellers last week and had been expected to move overseas but not to a club of the magnitude of the four-times English champions who have a squad filled with global talent.
"I didn't know there was any public information out there until I heard that this morning," Mariners coach Tony Walmsley told Australian media today.
"I do know that (Mariners owner) Mike Charlesworth has been in dialogue with the City Group,” he added.
Local media priced the transfer at around USD 500,000 for the Australian, who has 18 months left on his contract. Reports also suggested the player could be loaned to City's sister club and the Mariners' A-League rivals Melbourne City as part of the deal as Caceres does not hold a European passport so might struggle to gain a work permit.
Melbourne and Manchester City are owned by the City Football Group, which also owns New York City FC and holds a share in J-League outfit Yokohama F. Marinos.

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