A penalty from Jeremie Aliadiere and a Kevin Monnet-Paquet goal were enough to secure all three points for Lorient against Evian and keep the hosts on the fringes of European qualification in Ligue 1.
Betao scored a late consolation but it was not enough for the visitors, who lie one place above the relegation places in the table.
Lorient could have taken the lead after eight minutes but, when Lamine Gassama crossed from the right, Yann Jouffre's volley was blocked by Bertrand Laquait.
Aliadiere then fed Jouffre but his right-footed low drive was deflected for a corner by Laquait.
Laquait again saved Evian with 39 minutes gone when he kept out a 20-yard volley from Jouffre. Maxime Barthelme had crossed from the right and Jouffre's volley was on target until Laquait turned the ball over the bar.
But he could do nothing three minutes later when Betao fouled Aliadiere and the striker sent the goalkeeper the wrong way from the penalty spot.
Five minutes into the second half Monnet-Paquet got down the left but, when his cross found Aliadiere ideally placed inside the penalty area, the striker volleyed over the bar.
Jouffre then saw his shot from the edge of the area saved by Laquait after good work by Aliadiere.
Laquait pulled off a fine save from a fierce close-range shot by Jouffre, who had been released by Enzo Reale.
Evian looked to hit back, Yannick Sagbo freeing Milos Ninkovic on the edge of the penalty area, but the striker's shot on the run was well saved by Fabien Audard.
Lorient stretched their lead with 13 minutes to go when Jouffre's quick throw-in found Monnet-Paquet unmarked at the near post and his shot gave the keeper no chance.
With seven minutes remaining Ninkovic's superb through-ball set up Betao and he volleyed into the roof of the net, but it proved to be only a consolation.