Lens scored two goals in stoppage time as they came from behind twice to beat 10-man Slavia Prague.
Danijel Sturm produced a piece of excellent individual skill early in the second half to get the opener for Slavia, cutting inside to beat his man before bending the ball into the far corner.
His goal came just three minutes after the Czech side were reduced to 10 when Mikulas Konecny, who had only been on the pitch for three minutes after being brought on as a half-time substitute, brought down Abdallah Sima and denied a goalscoring opportunity.
Lens made the most of having an extra man and managed to get the better of the Slavia defence as they tired, with Sima turning in from close range after the hosts failed to clear the ball from their box.
Sturm thought he had snatched a late winner when he fired in from the edge of the box in the 88th minute, but Lens remarkably turned the game on its head.
Florian Thauvin fired in the equaliser in the first minute of stoppage time before Ruben Aguilar scored another two minutes later to inflict misery on Slavia.
Slavia travel to Azerbaijani club Sabah at 17:45 BST on 13 October in their next Champions League game, while Lens host Sporting at the same time.
