Phillips joined Celtic on loan last week in a four-month deal which will be reviewed by Liverpool in January.
His new club faced fierce rivals Rangers in the Old Firm derby on Sunday, but Phillips was not picked for involvement by Brendan Rodgers despite being available.
The former Reds manager explained the 26-year-olds omission from the matchday squad, insisting it was always the plan for him to sit out until after the international break.
It was always the plan. Coming in this was the game that he wasnt going to be able to make, revealed Rodgers.
Weve spoken with the Liverpool medical team, so we have to look after him. But he will be available for after the international break, hopefully.
Elsewhere, Fabio Carvalho was also unused as RB Leipzig ran out 3-0 winners away to Union Berlin.
The 20-year-old has registered just six minutes of Bundesliga football so far this season after joining RB Leipzig on loan earlier this summer.
It was a more fruitful weekend for Owen Beck, who notched his first assist for Dundee as they drew 2-2 at St. Johnstone.
His side did however surrender a two-goal lead as a late Max Kucheriavyi brace earned the home side a point.
Sepp van den Berg recorded 90 minutes for Mainz as they were thrashed 4-0 by Werder Bremen, with former Red Naby Keita not involved as he continues his recovery from an abductor muscle tear.
Harvey Davies, Luke Hewitson and Adam Lewis all featured for the duration of their weekend fixtures.
Anderson Arroyo, James Balagizi and Dominic Corness were reduced to substitute appearances.
Billy Koumetio, James Norris, Luca Stephenson and Jakub Ojrzynski were all forced to watch on from the sidelines after making their summer moves.
Calvin Ramsay and Rhys Williams were also out of action as they continued to nurse their respective injuries.
Tyler Morton was unavailable for Hull having not been registered in time following his deadline day switch.
Unused: Nat Phillips, Fabio Carvalho, Billy Koumetio, James Norris, Luca Stephenson, Jakub Ojrzynski
Injured: Calvin Ramsay, Rhys Williams
Unavailable: Tyler Morton