Monaco's hopes of catching Paris Saint-Germain in Ligue 1 have taken a huge hit with a 1-0 defeat to Evian TG on Saturday evening.
The home side started brightly and saw plenty of the early possession, but Facundo Bertoglio's shot from just outside the box fizzed wide of the far post.
Clarck Nsikulu then came closer to opening the scoring on 10 minutes, but his low shot from an angle was comfortably dealt with by Monaco goalkeeper Danijel Subasic.
Monaco continued to struggle to create anything, while another chance fell the way of Nsikulu but once again he could not beat Subasic this time from close range.
Daniel Wass put an effort from the edge of the box wide before Dimitar Berbatov skimmed a shot wide, but the two sides went in at the break goalless.
In the second half the hosts remained on top and again should have scored, but Cedric Cambon put a second-half header wide from just six yards out.
Then with five minutes to play Ricardo Carvalho handled in the box, which allowed Cedric Mongongu to step up and score from the spot for a big win.