Marcus Thuram and substitute Nolan Roux both scored in the space of seven second-half minutes to earn the visitors just a second win of the season.

Henry, whose team had never before lost a Ligue 1 match at home to Guingamp, has now suffered six defeats in his nine top-flight matches since taking over from Leonardo Jardim.

Monaco, the 2016-2017 champion, which has also crashed out of Europe, sits three points from safety and will need a significant upturn in form after the winter break if it is to avoid the drop.

Monaco has little more than two weeks to heal any psychological scars before a Coupe de France date with minnow Canet Roussillon.

Their next Ligue 1 assignment is away to Marseille on 14 January (AEDT).