Steven Gerrard's Rangers saw their 11-game unbeaten run in this year's Europa League come to a dramatic end as they threw away the lead three times in a 4-3 defeat at Spartak Moscow.
Both sides were the beneficiaries of comical own goals in a crazy first half which ended with Glenn Middleton putting the Scots 3-2 ahead, but Luiz Adriano and Sofiane Hanni both scored in the space of 71 seconds to snatch Spartak victory.
Rangers are now level on points with Spartak in an incredibly tight Group G, one point behind leaders Villarreal after the Spaniards' goalless draw with Rapid Vienna in Austria.
"For me, football is about levels and, if you don't defend properly and you don't do the basics well enough, high-level players and high-level teams normally punish you and that was the case tonight," Gerrard told the Rangers website.
Reigning Scottish champions Celtic gave themselves a lifeline in Group B, as Odsonne Edouard's 79th-minute strike saw them beat RB Leipzig 2-1 in their must-win clash at Parkhead.
Salzburg, semi-finalists last season, qualified for the next round with a 5-2 thrashing of Rosenborg in the group's other match, as Japanese forward Takumi Minamino scored a hat-trick.
Elsewhere, Eintracht Frankfurt reached the last 32 with their fourth win from as many group games by beating Apollon Limassol 3-2 in Cyprus, while Lazio joined them in progressing from Group H as goals from Marco Parolo and Joaquin Correa secured a 2-1 win over Marseille to eliminate last season's runners-up.
AC Milan stayed just a point adrift of Group F leaders Real Betis after Suso's second-half equaliser grabbed a 1-1 draw in Spain.
Record five-time winners Sevilla needed a late penalty from Ever Banega to claim a 3-2 victory at Akhisar Belediyespor, after having a man sent off, losing a two-goal lead and seeing the Turks miss a spot-kick of their own.