CELTIC could be boosted by the return of Cameron Carter-Vickers sooner rather than later.
The American centre-back has been out for around three weeks with a knock.
This has led to the defensive pairing of Stephen Welsh and Moritz Jenz in recent matches.
However, Postecoglou has confirmed that the ex-Tottenham stopper would be back in training today.
It was not made clear whether he would make the team to play St Johnstone or whether tomorrow's match would come too soon.
One player who will definitely be out, along with Callum McGregor, for the McDiarmid Park clash though is David Turnbull.
The former Motherwell starlet is suffering from tonsillitis.
Asked about squad rotation for Saturday, Postecoglou told the media: "There will be some changes naturally with Callum out. I wait and see how the boys are.
"Cameron Carter-Vickers and Aaron Mooy had a session yesterday and are due to join training this morning. Liel Abada is available again.
"David Turnbull will miss out due to tonsillitis which we hope will clear up by Tuesday."