The hosts started off strongly with Bamba Dieng particularly bright in the early stages. The striker dragged his first attempt wide, before Robin Risser saved from him from close range.
Luckily for Dieng though, he got a second bite of the cherry to stab Lorient in front with the rebound.
That goal broke a run of three successive Ligue 1 head-to-heads without scoring for Les Merlus, and Lens had no answer before the half-time whistle.
Florian Thauvin, who boasted as many contributions across his previous five league clashes against Lorient, came closest to equalising for the visitors, as Yvon Mvogo superbly saved two of his fierce strikes.
However, Lens had scored in their last 15 Ligue 1 fixtures, and they made it 16 early in the second half with Mamadou Sangare feeding Odsonne Edouard, who drove into the box before sweeping beautifully into the bottom corner to put the title chasers level.
Thauvin then had yet another chance to score following a corner, but his header looped onto the roof of the net.
It was the tale of the strikers in this match, and Lorient’s goalscorer was surprisingly replaced by Aiyegun Tosin. But the substitution paid off straight away, when Arsene Kouassi’s cross found Tosin in the box, and after mistakenly stamping on the ball, he knocked it past Risser.
Now, chasing another equaliser, Thauvin tried his best to squeeze the ball home from a tight angle in the latter stages, but Mvogo was again equal to his effort.
Lens came up short in the end and duly slipped to just their second defeat in nine away league games (W6, D1), while additionally missing the chance to leapfrog Paris Saint-Germain at the summit.
Lorient, meanwhile, have moved up to eighth as a result of their success, and are now knocking on the door for the European places, after just a second head-to-head victory in 11 Ligue 1 matches (D3, L6).
Flashscore Man of the Match: Arsene Kouassi (Lorient)
