Guingamp's Ronnie Schwartz sought to test the Montpellier resolve early on as he hit a shot from distance, leaving Geoffrey Jourdrento to save comfortably in the centre of goal.
Anthony Mounier should have put Montpellier a goal to the good after 10 minutes, only to crash his effort over the crossbar from inside the box, before Guingamp's Rachid Alioui dragged a shot wide down at the other end.
The hosts' Souleymane Camara produced the best effort of the first half, but Mamadou Samassa did excellently to get down low to his bottom right corner to keep things level.
Guingamp were to be broken after half time however, as Camara finally got his way with a hard-struck shot into the bottom corner, when he was picked out by a clever ball from Jonas Martin.
The away side should have had an equaliser with just under half an hour to play, but Mustapha Diallo saw his header smash back off the crossbar with the keeper looking stranded.
However, there was another twist left in the game as Kevin Berigaud picked out Montano inside the box, who made no mistake by lashing past Samassa, who was later given a straight red as the game ended 2-1.