On-loan Arsenal striker Folarin Balogun scored a dramatic stoppage-time equaliser for Reims against 10-man Paris St-Germain.
The result means PSG miss the opportunity to open up a five-point lead over Lens at the top of Ligue 1.
Neymar had opened the scoring for PSG who then had midfielder Marco Verratti sent off.
Balogun's equaliser arrived in the 96th minute to extend Reims' unbeaten run to 14 games in all competitions.
The England under-21 international has now scored 11 goals in Ligue 1 this season, the most of any player aged 21 or under in Europe's big five leagues.
Reims, coached by 30-year-old Belgian-born Englishman Will Still, acquitted themselves well throughout against a PSG starting XI that contained Lionel Messi, Kylian Mbappe and Neymar for the first time since the World Cup.
PSG have now dropped points in three of their four league games in 2023 and their form will be a concern with the first leg of their Champions League last-16 tie against Bayern Munich just over two weeks away.