Lyon's bid to qualify for next season's Champions League continued to falter as they succumbed to Grzegorz Krychowiak's second-half penalty at Reims.
The result moved Reims four points clear of the bottom three but meant Lyon's run of games without a win was extended to five. Remi Garde's men now sit outside the top three for the first time in 2013.
Beforehand, Garde said he still thought second place was an achievable target for his players but a third successive defeat means they have much to do over the final seven games.
Les Gones' lack of self-belief was evident in a first half dominated by the hosts.
Only Lyon goalkeeper Remy Vercoutre excelled, his first save coming after five minutes to palm clear Mohamed Fofana's powerful header.
Five minutes later, Diego came close for Reims with a low volley which flashed inches wide.
The onslaught continued with Vercoutre saving his side again, blocking Christopher Glombard's shot after he had been picked out by Gaetan Courtet's pass.
Former Montpellier goalkeeper Vercoutre ensured there were no goals before the break with an even better stop on the half-hour mark when he acrobatically blocked Courtet's volley after good work from the impressive Diego.
Having been on the back foot for the entire first period, Lyon almost went in front within a minute of the restart.
Alexandre Lacazette released Maxime Gonalons down the right and he skipped past Diego before unleashing a shot which crashed back off the post.
Reims soon reasserted their superiority and took the lead seven minutes later.
Diego was fouled by Milan Bisevac inside the area and Krychowiak made no mistake from the spot.
Reims goalkeeper Kossi Agassa produced his first save of the afternoon to keep out Clement Grenier's drive after 68 minutes before Vercoutre kept Lyon's deficit at one by deflecting Antoine Devaux's effort away with his feet.
Lyon rarely mustered a serious attack in the final 22 minutes as Reims held on for their third win on the bounce.