Steven Gerrard takes his side into Sunday’s Glasgow derby on the back of three defeats in four matches.
Bayer Leverkusen dominated in every area of the park to stroll to a 3-1 victory that makes the second leg look like a formality. Prior to beating Ross County on Sunday Gerrard’s side had lost to Hearts and Hamilton.
Gerrard was boosted by the return from injury of Scott Arfield and captain James Tavernier but as the match ran away from them the experienced duo had to be substituted.
Leverkusen had to wait until the 37th minute for the breakthrough when Kai Havertz put the visitors in front from a penalty awarded by VAR.
Charles Aranguiz doubled the lead in the 67th but eight minutes later George Edmundson threw the homeside a lifeline when he found himself unmarked and headed home a corner.
There was no fairy-tale ending however with substitute Leon Bailey netting for Leverkusen in the 88th minute to put the German’s firmly in the driving seat.
Celtic go to Ibrox with a 13 point advantage at the top of the SPFL.