Paris St Germain's Ligue 1 title charge suffered a surprise blow as they slumped to defeat away to the 10 men of relegation-battling Reims.
Zlatan Ibrahimovic had a goal controversially disallowed early in the second half, and Reims then had Christopher Glombard sent off for a second bookable offence before the hour mark.
But Reims still ran out winners as Grzegorz Krychowiak scored the only goal in the 64th minute.
The result means that Lyon can move level on points with PSG by beating Brest away from home tomorrow.