Brendan Rodgers' side fell behind in the first game in Glasgow last week but came back strongly to take a 3-1 lead to Trondheim.
Greek champions AEK Athens await the winners, with ties to be played on August 7/8 & 14.
Champions pathway - Qualifying round three
Celtic (SCO) or Rosenborg (NOR) v AEK Athens (GRE)
Salzburg (AUT) v Shkendija (MKD)
Crvena Zvezda (SRB) or Suduva (LTU) v Spartak Trnava (SVK)
Kukes (ALB) or Qarabag (AZE) v BATE Borisov (BLR) or HJK Helsinki (FIN)
Astana (KAZ) or Midtjylland (DEN) v Dinamo Zagreb (CRO)
CFR Cluj (ROU) or Malmo (SWE) v Ludogorets Razgrad (BUL) or Vidi (HUN)
