Ndong has been AWOL for four months, before being pictured at Newcastle Airport this morning, but Sunderland at not expecting their club-record signing to attend training.
Ndong has been seeking a move away from Wearside for some time, but with the Portuguese transfer window closing earlier in the week it appears that is no longer a realistic home.
As such, he could now be willing to play for the club again. However, he could be falling into the same trap that Papy Djilobodji has already succumbed to. The 'Black Cats' man also refused to turn up for pre-season or training, and when he finally did reappear it was then that he had his contract terminated.
Club owner Steward Donald has previously tweeted that he had no idea where the player was, and manager Jack Ross was similarly unaware.
"There has been no contact with me. In terms of me having him back in the playing squad, we have gone a long way beyond that point, I think," Ross said.