Having secured a dream date with a Basel club rich in modern history including regular appearances at the elite-level Champions League stage, the Crues head home down by 2-0.
It proved another European performance of pride and passion by the Irish League outfit ahead of next Thursday’s home tie at Seaview.
That first-leg reverse arrived despite the hosts at St Joseph-Park losing Taulant Xhaka to a red card just past the half-hour mark.
Xhaka’s dismissal for two bookable offences came on 33 minutes.
However, the deficit on the field lasted fewer than four minutes before Crusaders had to react to a deficit on the scoresheet.
Basel broke the deadlock when Dan Ndoye steered a shot beyond Jonny Tuffey.
The initial exchanges proved competitive as Basel pushed for the upper hand but Ben Kennedy forced the home goalkeeper into one save before Crues shot-stopper Jonny Tuffey had to be alert.
Billy Joe Burns and Chris Hegarty produced key defensive contributions before the tie turned around a red card and first goal.
Tuffey made an early second-half save but Basel managed to double the advantage with a clever and clinical backheel finish by Adam Szalai.
Basel created additional openings and attempts both wide and high.
Kennedy then came close to finding Paul Heatley in a promising position before the Crues had to survive the risk of an own goal.
Crusaders had one header wide off a corner-kick late on and a Kennedy free-kick caused problems for goalkeeper Marwin Hitz.
But Tuffey and Hegarty combined to keep the deficit at two goals before Johnny McMurray’s header forced Hitz into a fine save.
One late header proved just off target and Hitz was on hand to deny McMurray in the closing moments.
Basel: Hitz, Sergio-Lopez, Comas (Males, 76), Pelmord, Padula, Frei Xhaka, Burger, Ndoye (Amdouni, 67), Szalai (Millar, 67), Ltaief (Tushi, 81).
Subs (not used): Salvi, De Mol, M.Lang, Djiga, Hunzikwe, Chipperfield.
Crusaders: Tuffey, Hegarty, Burns, O’Rourke, Larmour, Clarke (McMurray, 76), Kennedy, Lowry, Heatley, Winchester (Weir, 75), Forsythe.
Subs (not used): Pauley, Lecky, Ebbe, Patterson, Owens, McKeown, Robinson, Barr, Morrow.
Referee: A.Kourgheli.