Sergio Ramos (L) is working his way back from a calf injury. AFP
Ramos has not played for PSG since joining the French giants on a two-year deal from Real Madrid in July, and has been training alone on his recovery from a calf injury.
"We're following his progress from day to day. We hope he'll be back as soon as possible, but for the moment we can't say when," Pochettino told reporters ahead of Sunday's trip to Rennes in Ligue 1.
"Injured players go through things differently from the group. It's difficult to fit in without being able to take part in the team training sessions or matches.
"But he's an experienced player. When he's able to get involved he'll adapt quickly."
In addition to the ongoing absence of Ramos, PSG will be without Layvin Kurzawa and Julian Draxler against Rennes due to illness.
PSG have won all eight matches in the league to start the season and sit six points clear of second-placed Lens with a game in hand.
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