A disastrous opening 20 minutes left Rangers' hopes of Champions League qualification hanging by a thread, as a clinical Club Brugge side tormented the hosts inside a seething Ibrox.
After a stuttering start to the season, the lure of Champions League riches offered potential salvation and credit in the bank for new head coach Russell Martin, who remains under scrutiny from many fans after an unconvincing start to the season.
Questions about Rangers' defensive frailties have lingered in recent weeks, and fans' worst fears were realised when three wretched early concessions left the Scottish Premiership shellshocked.
Danilo's second-half tap in gives them a slither of hope for next Wednesday's second leg in Belgium, but their performance levels would need to be hugely improved to give them any chance.
It took just three minutes for Ibrox to be stunned into first silence, then anger, when Nasser Djiga inexplicably failed to deal with a bouncing ball inside his half, allowing Romeo Vermant to race in and dinked over Jack Butland from 30 yards.
A Rangers side already low in confidence were rattled again after seven minutes, when a further lapse in concentration left Jorne Spileers unmarked to sweep in from a corner. The boos were amplified.