The 26-year-old has not been involved in any of Tottenham’s matches this season even as Postecoglou made nine changes for the Carabao Cup penalty shootout defeat to Fulham.
Ndombele is now weighing up a season-long loan move to Genoa having spent last season at Italian champions Napoli and six months at Lyon the season before.
Spurs are struggling to recoup any of the £63million spent on their club-record signing, who has been a disappointment since joining from Lyon.
The seven-time France international still has two years left on his £120,000-a-week contract.
Postecoglou confirmed on Tuesday night that he is looking to cut down the size of his squad with as many as seven Spurs players available to leave.
He said: “We need to trim the squad and get it to a more manageable state and see what's available for us to bring in players to strengthen a couple of players we may need.”