Paris Saint-Germain slipped to a first defeat of the season as second-placed Lens demonstrated their Ligue 1 title credentials with an impressive 3-1 victory at Stade Bollaert-Delelis.
Goals for Przemyslaw Frankowski, Lois Openda and Alexis Claude-Maurice in an entertaining New Year's Day contest reduced PSG's lead at the summit to four points.
Hugo Ekitike equalised in the first half, but Christophe Galtier's side were second best in their first game of 2023 as they await the return of Lionel Messi following his World Cup triumph with Argentina.
It was a dream start to 2023 for Lens boss Franck Haise, who celebrated his 100th match in charge in style.
A raucous crowd did not have to wait long for fireworks, with Frankowski on hand to apply the finish after Gianluigi Donnarumma could only parry Massadio Haïdara’s strike into his path five minutes in.
PSG promptly struck back three minutes later, when Ekitike poked a finish beyond Brice Samba, though the Lens keeper claimed the ball was kicked out of his hands by the forward.
Lens took that setback in their stride, and they were back in front with a goal on the break just before the half-hour mark, Openda taking a pass from captain Seko Fofana and beating Marquinhos before firing under Donnarumma.
Things went from bad to worse for PSG when Openda turned provider with a superb backheel for Claude-Maurice to rifle home two minutes after the restart.
There was no way back for the Parisian giants as Lens showed they are capable of putting up a serious title fight.