In a nightmare beginning to the first leg, Gers defender Nasser Djiga inexplicably allowed a long ball past him in the third minute and grateful visiting striker Romeo Vermant coolly lofted the ball over stranded goalkeeper Jack Butland.
And further strikes from Jorne Spileers and Brandon Mechele had the visitors 3-0 up after just 20 minutes.
Brazilian striker Danilo pulled a goal back four minutes after the break and the home side rallied, but the Belgian outfit stood firm.
The return game against Nicky Hayen’s men in Belgium next Wednesday will require a huge turnaround, albeit the Govan club are assured Europa League group phase football at least.
Wins over Panathinaikos and Viktoria Plzen in previous qualifiers revealed flaws in Russell Martin’s new-look Gers side and raised concerns in the stands, as did back-to-back draws to start the William Hill Premiership campaign.
And once again the former Southampton boss incurred the ire of the Light Blue legions.
Martin made 10 changes for Saturday’s 4-2 Premier Sports Cup victory over Alloa and seven for the visit of the Belgian outfit.
The news that elicited the most surprise was that 19-year-old England youth international Jayden Meghoma, who signed on loan from Brentford on Sunday, went straight in at left-back with Max Aarons preferred to experienced club captain James Tavernier at right-back.
Jack Butland, John Souttar, Mohamed Diomande, Oliver Antman, Djeidi Gassama, and Nicolas Raskin all returned.
Greece international Christos Tzolis, who scored for Greece against Scotland at Hampden Park in March and who has been linked with a move to Crystal Palace, started for the visitors, while former Liverpool keeper Simon Mignolet was in goal.
All eyes were on Meghoma, who spent last season on loan at Preston, and he started positively.
Rangers manager Russell Martin (top) pats Hamza Igamane on the back as he climbs off the the turf after final whistle. Photo: PA Wire
But a horror mistake by Djiga allowed Tzolis’ pass to give Vermant an easy finish which stunned everyone inside the ground.
The Gers fans were coming to terms with the needless loss of a goal when Tzolis’ corner from the right was knocked past Butland by the unmarked Spileers from 12 yards.
The boos that rang round the ground intensified when Mechele, making his 500th appearance for Brugge, stepped all too easily in front of Danilo just outside the Rangers box and gave Butland no chance with an arrowed right-footed drive.
Light Blues midfielder Joe Rothwell clipped the outside of a post with a free-kick from 25 yards in the 26th minute.
But it was not the signal for a comeback as Butland brilliantly beat away a drive from Carlos Forbes, with the home defence again split open.
A three-goal deficit at the break left the Gers support in a state of shock but they got a lifeline when Danilo slid in to convert an enticing cross from Meghoma.
Brugge stepped up the pace and amid a flurry of corners, Butland made a fine from Joel Ordonez.
Gassama’s angled-drive skipped inches past the far post before Mohamed Diomande and Danilo were replaced by Hamza Igamane and Thelo Aasgaard.
Gassama had the ball in the Brugge net in the 78th minute but French referee Francois Letexier was asked by VAR to check his pitchside monitor and quickly decided that Mignolet had the ball in his hand before it was bundled into the net.
The Light Blues second-half display was heartening but it was a chastening first 20 minutes which keeps the spotlight on Martin.
