A patched up Paris Saint-Germain - missing seven players through coronavirus, including Kylian Mbappe and Neymar - suffered defeat to RC Lens in their Ligue 1 opener.
The French top-flight kicked off towards the end of August, but Thomas Tuchel's side were given extra time off following their Champions League exploits.
Less than three weeks after their defeat in the final to Bayern Munich, Tuchel's men were in action at newly-promoted Lens without a number of first-team players.
The hosts carved up the best chance in the first half, Igniatius Ganogo denied by the post after a threatening run, while 18-year-old Kays Ruiz-Atil showed some promise for PSG, flashing a shot just over.
Alarm bells had been ringing, though, and in the 57th minute the hosts broke the deadlock, with 20-year-old goalkeeper Marcin Bulka - replacing Keylor Navas, who had tested positive for Covid-19 - making a terrible error, passing straight to Ganogo, who this time made no mistake with a cool finish.
Bulka, making only his second appearance, helped make amends with a fine save to deny Simon Banza, but the damage had been done and PSG - who registered just one shot on target - never looked like restoring parity, as they fell to a rare loss.
TALKING POINT - RC Lens take full advantage of depleted PSG
Five thousand home supporters were in attendance to see their newly-promoted side host the might of PSG, and there was a strange sense of confidence at Stade Bollaert-Delelis before kick-off as the Ligue 1 champions rolled into town. Without Neymar, Mbappe, Keylor Navas, Mauro Icardi and co, Lens knew they would never have a better opportunity to beat the Parisians.
Lens had started their campaign with defeat to Nice, but they showed no fear and the depleted PSG little respect, fully deserving their famous victory. It was a night to forget for Bulka, who in the absence of Navas, had a chance to make an impression, only to cost his side dear. Things went from bad to worse for PSG as Presnel Kimpembe limped off with a knee injury late on.
With so many players missing due to Covid-19, it begs the question if the game should have been postponed. PSG may as well have started the campaign with a handicap, and it doesn't get any easier as they prepare for a home match with fierce rivals Marseille on Sunday.
MAN OF THE MATCH - Igniatius Ganogo (RC Lens)
Leading the home side's attack, Ganogo held the ball up well, made clever runs and ultimately grabbed the match-winner.
Lens: Leca 7, Gradit 6, Bade 6, Medina 6, Michelin 7, Doucoure 6, Perez 6, Sylla 7, Kakuta 6, Ganago 8, Banza 7.. subs: Sotoca 6, Cahuzac 5, Mauricio N/A, Jean 5, Boura N/A.
PSG: Bulka 4, Kehrer 5, Kimpembe 5, Kurzawa 6, Bernat 5, Herrera 5, Gueye 5, Verratti 5, Sarabia 5, Kalimuendo 5, Ruiz-Atil 5.. subs: Bakker N/A, Dagba 5, Jese 5, Diallo 5.
17' - Lens hit the post! Oh, what a let off for PSG! Good hold up play initially from Ganago, he then knocks the ball into space, carves inside and creates the opening for a shot on the edge of the box. His curled effort smacks off the bottom of the post!
57' - GOAL! RC Lens 1-0 PSG (Ganago): Oh dear me, Bulka has had an absolute nightmare! The young PSG goalkeeper passes straight to Ganago who takes full advantage by slotting it home to give the hosts the lead!
63' - Great save! Bulka goes someway to redeeming himself. He spreads himself to stop Banza's stooping header. That would have been a lovely goal and would have put Lens almost out of sight!
Ignatius Ganago has scored three goals against PSG in Ligue 1, his favourite opponent in the top-flight.