Jonathan David's first-half penalty saw Lille stun Champions League holders Real Madrid on Wednesday, handing Los Blancos their first loss in any competition since January.
Fifteen-time European champions Madrid had not tasted defeat since going down to Atletico Madrid in the Copa del Rey 36 games ago, while they were also unbeaten in their last 14 Champions League outings.
But Los Blancos were flat from the off in France and had a couple of warnings before David converted from the spot in first-half stoppage time, after Eduardo Camavina handled from Edon Zhegrova's free-kick.
Andriy Lunin, standing in for the injured Thibaut Courtois, had earlier clawed David's attempt onto the post, while Endrick called Lucas Chevalier into action at the other end after becoming the youngest player to start for Madrid in the Champions League, at the age of 18 years and 78 days.
Zhegrova went close to a second Lille goal after the break, before Carlo Ancelotti introduced the fit-again Kylian Mbappe from the bench in a bid to find a leveller.
However, Los Blancos were unable to salvage a point with Dani Carvajal heading wide and Chevalier making an instinctive save to deny Antonio Rudiger at the death.
The result sees Lille move level with Madrid in the competition's new-look league phase, on three points apiece after two matches.
Data Debrief: Lille halt imperious Madrid
Madrid entered Wednesday's game unbeaten in their last 14 Champions League outings, but they were kept out by a resolute Lille rearguard – though they also had Chevalier to thank as Los Blancos failed to score from chances worth 2.09 expected goals (xG).
This is Madrid's first Champions League loss since they were crushed 4-0 by Manchester City in the 2022-23 semi-finals, and their first in the group stages since October 2022 versus RB Leipzig (2-3).
Ancelotti's men started with a home victory against Stuttgart on matchday one, but they are now winless in three straight European away games, drawing two and losing one.
That is their longest such run since November 2016, when they endured a run of four without victory on their travels (three draws, one defeat).