The Hoops trained at Celtic Park on Tuesday and images from Sky Sports showed Cameron Carter-Vickers and Carl Starfelt both sat out the session.
The defensive duo are now confirmed absentees for the game against the Bundesliga side as they continue their recovery from recent injuries.
Celtic travel to the Red Bull Arena looking for a first win in this season’s group stage after taking one point from games against Real Madrid and Shakthar Donetsk.
They meet a Leipzig side currently sat in mid-table in the Bundesliga after collecting 11 points from their opening eight league games - although they did claim a 4-0 home win against Freiburg thanks to two goals apiece from Christopher Nkunku and Timo Werner at the weekend.
Speaking ahead of the trip to Germany, Celtic boss Postecoglou told the club website: “After the weekend’s game everyone got through it really well from a physical standpoint, which is important.
“We’ll recover from the game, and prepare. This is pretty much going to be our routine between now and the break, so we know what we need to do.
“The recovery process is going to be important with all the football we have and how we give the players feedback on games and how we prepare them for games.
“That means limited time out on the training field but we still want to maximise as much as we can the quality of our football there, but most of it will be just getting in to this routine of recovery, review and preparing for the next game.”
Midfielder Aaron Mooy did not travel with the squad due to a niggle, while Liel Abada sits the game out due to a clash with Jewish holy day Yom Kippur.
However, there was some good news for Postecoglou as Greek striker Georgios Giakoumakis returned to training after missing the win against Motherwell.
The former VVV-Venlo forward has three goals in nine appearances in all competitions so far this season and has featured in both of Celtic’s group stage fixtures.