Lens beat Ligue 1 leaders Paris St Germain 3-1 on Sunday to give the champions their first league loss of the season, narrowing the gap at the top between the two teams.
PSG were without Neymar, who was suspended after getting sent off against Strasbourg on Wednesday, and Lionel Messi who is continuing his post-World Cup recovery.
The result means Christophe Galtier's side are on 44 points from 17 games, four points ahead of Lens in second.
The hosts took an early lead after five minutes when a deflection from PSG keeper Gianluigi Donnarumma went to an unmarked Przemyslaw Frankowski, who volleyed the ball into the open net.
Hugo Ekitike equalised for PSG three minutes later when the striker reached a cross before Lens goalkeeper Brice Samba and tapped the ball in.
Lens striker Lois Openda restored his side's lead in the 28th minute when he got a through ball from Seko Fofana and ran into the box, where he beat defender Marquinhos before finishing into the lower-right corner of the goal.
French forward Alexis Claude-Maurice made it three for Lens two minutes into the second half to seal the win.
FIFA President Gianni Infantino proposed an outside review of how the governing body makes major decisions on Monday, acknowledging in a letter to members that its handling of a now-abandoned investment plan had caused concern.
Captain Marquinhos has snatched the winner as champions Paris St Germain won 2-1 at troubled Olympique de Marseille in Ligue 1 on Sunday, condemning the hosts to a fifth successive loss and a spot in the relegation zone.
Anders Dreyer has scored his 10th and 11th goals on either side of halftime and visiting San Diego FC earned a 2-2 draw against Lionel Messi and defending MLS Cup champions Inter Miami on Sunday night.
Manchester City head into the first international break three points clear at the top of the Premier League after Antoine Semenyo's double sealed an enthralling 5-3 home win over Sunderland, for whom Brian Brobbey grabbed a hat-trick, on Sunday.