Rosenborg manager Per Joar Hansen said he was worried by the finishing prowess of Jordan Owens and the striker demonstrated why.
Owens' sensational first half strike rocked the Norwegian giants and even though Nigerian striker John Chibuike and Jonas Svensson replied for the visitors, the Shore Road men can reflect on a performance full of guts and character.
The Crues gave their full-time opponents several genuine scares and although they will travel to Trondheim next Thursday with low expectations of keeping their Europa League dream alive, Stephen Baxter's men deserve a firm pat on the back.
Rosenborg, who left Seaview three goals to the good a year ago after a first leg tie, came up against a more composed and intelligent Crusaders challenge this time round.
Hansen's troops are 14 games into their season but the Crues, still a work in progress in pre-season, rose to the occasion with a spirited showing.
But there was a sting in the tail for the Shore Road men at the end of an entertaining first half in which the hosts played with little fear against classy opponents.
Owens' opener was a stunning strike and the striker could have been chasing a first half hat-trick had he converted an easier opportunity in the 31st minute.
Crusaders absorbed some early pressure from the visitors but the anticipated bombardment never materialised.
In fact, Rosenborg keeper Alexander Hansen pressed the panic button on a few occasions as the Hatchetmen cut through their rearguard.
But Crues keeper Sean O'Neill was tested in the ninth minute when a Borek Dockal free-kick caused confusion and Tore Reginiussen's close range effort was deflected to safety by the shot-stopper.
Rosenborg looked for the early goal to crush the Crues' confidence and on 13 minutes Nicki Bille Nielsen floated a shot over the crossbar.
On 23 minutes, Owens came to the party in spectacular fashion. Paul Heatley, a livewire on the left-wing, teed up the hitman and he unleashed a delightful curling strike from 23 yards which sailed into the top corner of the net.
Five minutes later the visitors came close to an equaliser but O'Neill produced a superb block with his legs to foil Nielsen.
In the 31st minute Owens came within a foot of grabbing his second when racing onto another pass from Heatley but this time his low drive whistled past the woodwork.
You sensed it would be a costly miss and the home side cursed their luck a minute into first half added time when Nielsen's floated cross was headed home from close range by Chibuike.
A long range free-kick from Chris Morrow (pictured) illuminated a quiet start to the second half but Hansen was untroubled.
Rosenborg struggled to carve out any clear cut chances but they found a way past the solid home defence in the 77th minute.
Borek Dockal's low cross into the box was confidently stroked home by Jonas Svensson, the ball travelling under O'Neill's body and locating the net.
Crusaders legs, not surprisingly, tired in the second half, but the players stuck to the task and with a little luck, could be heading to Norway with the sides level.
Eamon McAllister's late shot lacked power and keeper Hansen made a simple save.
A third Rosenborg goal would have been cruel on the hosts but the Crues frustrated the top seeds and their players left the pitch to warm applause from the home support.
St Johnstone face the winners of this tie in the next round and new boss Tommy Wright, looking on from the stand, would have been impressed by the organisation and commitment of both sides.
The part-timers, in particular, secured a moral victory.
Crusaders: O'Neill, Robinson, Magowan, Coates, McClean, McAllister, Cleary, Heatley, Morrow, Snoddy, Owens. Subs: Watson (for Cleary 68 mins); McCutcheon (for Snoddy 77 mins); McMaster for Heatley (83 mins), Lacroix, Leeman, Adamson, King.
Rosenborg: Hansen, Gamboa, Reginiussen, Ronning, Dorsin, Berntsen, Selnaes, Svensson, Chibuike, Nielsen, Dockal. Subs: Jensen (for Svensson 83 mins); Strandberg (for Selnes 85 mins); Mikkelsen (for Bernsten 90 mins)
Referee: Hugo Miguel (Portugal).