Ten-man Arsenal suffered their first away defeat by a French club in European competition in the first leg of their Europa League last-16 tie at Rennes.
The Gunners appeared to be cruising when Alex Iwobi’s early cross from the left drifted past home goalkeeper Tomas Koubek, into the right corner.
But Benjamin Bourigeaud’s stunning strike, which flew into the top right corner, levelled matters immediately after Sokratis Papastathopoulos’ dismissal for a second booking.
Unai Emery’s side fell behind when Nacho Monreal deflected Mehdi Zeffane’s cross from the right past his own goalkeeper Petr Cech.
And Ismaila Sarr’s diving header in the closing stages compounded a miserable evening for Arsenal.
However, it was no more than the hosts deserved as they capitalised on their man advantage to bombard the visiting goal after the break.
Arsenal will now hope to repeat their heroics from the last-32 stage, where they overturned a 1-0 first-leg deficit against Belarus side Bate Borisov to progress with a 3-0 home victory.
Follow all the action from the Europa League including Rennes v Arsenal
Arsenal arrived at Roazhon Park having never lost an away game against French opposition.
For large parts of the first half, that record looked like remaining intact as they gathered an early lead courtesy of Iwobi and controlled possession.
But instead of extending their advantage, with Lucas Torreira seeing a shot superbly saved by Koubek, and Pierre-Emerick Aubameyang also testing the Czech goalkeeper, they proved architects of their own downfall in an 86-second spell.
Having already been booked for a foul on Hatem Ben Arfa, Greece defender Papastathopoulos foolishly tugged at Sarr’s shirt to earn his second yellow card of the evening.
From the resulting free-kick, Bourigeaud’s equaliser shifted the momentum of the game in the hosts’ favour.
With attacking midfielder Henrikh Mkhitaryan deployed as a makeshift right-back, Arsenal faced one-way traffic in the second period.
Cech, who replaced Bren Leno in goal for Emery’s side, produced a string of superb saves, denying Adrien Hunou, Sarr and Ben Arfa twice with the score at 1-1.
But he was helpless to prevent Rennes’ second of the night with the Arsenal defence clocking off to allow Zeffane to reach the ball before it flicked off Monreal into the top corner.
And as Arsenal attempted to see out the game with only a one-goal deficit, they carelessly lost possession to inflict further damage on themselves.
James Lea Siliki escaped on the left and delivered the perfect ball for an unmarked Sarr to head past Cech at the back post.
Until this tie, Rennes’ sole experience of English opposition in European competition was an away goals defeat by Aston Villa in the 2001 UEFA Intertoto Cup semi-final.
But this unlikely and famous victory over Arsenal has now given Julien Stephan’s side, who lie 10th in Ligue 1, a realistic prospect of continuing their most successful campaign in Europe.
In 2011-12, they were unable to advance beyond the group stage of this competition. They also twice failed in the Uefa Cup group stage, in 2005-06 and 2007-08, before it was rebranded as the Europa League.
While Emery was able to spend more than £26m on Torreira alone last summer, Stephan’s achievements have come with a more modest outlay.
Former Newcastle and Paris-St-Germain forward Ben Arfa, who tormented Mkhitaryan at times, arrived on a free, while ex-Lyon midfielder Clement Grenier, who has five caps for France, hardly put a foot wrong in midfield with a 90% pass accuracy.
There were also signs that Sarr, who has been linked with Barcelona, could prove a handful in the return leg at Emirates Stadium.
The 21-year-old constantly tested Monreal for pace, skipping away from him on several occasions and had three efforts on goal before getting his reward at the death.