Scott Sinclair boosted Celtic's chances of qualifying for the next round of the Europa League with the only goal in a 1-0 win at Rosenborg that ended the Norwegian side's hopes of progressing.
Sinclair headed in an excellent right-wing cross from James Forrest shortly before half-time to earn a crucial Group B victory at Lerkendal Stadium on Thursday.
Celtic host Salzburg - who have already qualified as the pool's winners - on matchday six next month knowing a draw is enough to send the Scottish champions into the knockout stages.
Tom Rogic and Odsonne Edouard missed Celtic's best chances in a lively opening from Brendan Rodgers' side, who took the lead in the 42nd minute.