After soaking up some early pressure, Toulouse had a pair of quickfire chances on the quarter hour mark.
First, they struck on the break with Josh King feeding top scorer Zakaria Aboukhlal, who looked as though he would round Herve Koffi, only for the debutant keeper to stand tall and stop him in his tracks.
The Burkina Faso international was then called into action two minutes later when he tipped a first-time effort from King around the post.
At the other end, Guillaume Restes saved comfortably from Przemyslaw Frankowski’s strike from the edge of the box, while M'Bala Nzola should have done better when he curled an effort wide of the post just before the break.
Lens continued to pressurise Toulouse after the break, and though Violets defender Charlie Cresswell bravely blocked Florian Sotoca’s vicious volley just short of the hour mark.
There was the growing sense of an imminent Lens goal at this point, but referee Hakim Ben El Hadj Salem changed the flow of proceedings with a damaging dismissal for Lens.
He initially booked half-time sub David Pereira da Costa for a rake on the calf of Djibril Sidibe, but went to the VAR screen and upgraded his call to a red card.
Predictably, the momentum turned against the Sang et Or, as Toulouse looked to grasp what was now a very real opportunity to get their first away head-to-head win since March 2011.
Ten minutes later, the video assistant would rule in the favour of Les Violets again after Malang Sarr’s clumsy barge in the back of Aboukhlal brought about a penalty.
The Moroccan international dusted himself down and rolled it coolly into the bottom corner, despite the best attempts of the sold-out home crowd to put him off.
From there, a second goal would surely have sealed three points, but Koffi’s lightning reactions denied Yann Gboho from close range with 10 minutes remaining. Despite Frankowski and teenage debutant Gabin Capuano pushing hard for an equaliser for the hosts, it would not come as Will Still’s men’s unbeaten league record ended at three.
Flashscore Man of the Match: Zakaria Aboukhlal (Toulouse)