Europa League: Celtic play Salzburg, Leipzig and Rosenborg
Celtic will meet the Austrian champions along with familiar Norwegian opponents.
Celtic have been drawn in Group B of the Europa League along with Salzburg, RB Leipzig and Rosenborg.
Top seeds Salzburg return to Glasgow four years after they faced Celtic in the group stages. They sides drew 2-2 in Austria with Salzburg winning 3-1 at Parkhead.
The Austrian champions got to the semi-final stage last year, only going out to Marseille in extra-time.
The Hoops also face tough opposition in Bundesliga side RB Leipzig who reached the quarter-finals last year after being eliminated from the Champions League.
Brendan Rodgers' side booked their place in the group stages with a 4-1 aggregate win over Lithuanian champions Suduva on Thursday night.
The Scottish champions dropped in to the Europa League after they were eliminated from the Champions League by AEK Athens in the third qualifying round.
The Hoops saw off Alashkert and Rosenborg in the previous two rounds.
Last season, Rodgers' side were knocked out of the Europa League in the last 32 by Russian side Zenit St Petersburg after finishing third in their Champions League section.
Match day 1 (September 20) - Celtic vs Rosenborg 8pm
Match day 2 (October 4) - Salzburg vs Celtic 5:55pm
Match day 3 (October 25) - RB Leipzig vs Celtic 5:55pm
Match day 4 (November 8) - Celtic vs Leipzig 8pm
Match day 5 (November 29) - Rosenborg vs Celtic 5:55pm
Match day 6 (December 13) - ~Celtic vs Salzburg 8pm