Riding the wave of three consecutive Ligue 1 victories, Lens took it to last-placed Metz in the opening exchanges, with the hosts looking short on confidence throughout the half.
Odsonne Edouard was the most obvious goal threat and twice found space at the far post, but his first chance saw him tamely shoot into the arms of Jonathan Fischer before completely missing the target a few minutes later.
Those missed chances allowed the hosts to grow into the game, and they should’ve hit the front before the interval. Koffi Kouao did well on the right to get a shot away, and although it appeared to be speculative at best, Robin Risser parried it into the path of Habib Diallo, only for the striker to skew the ball wide with the goal gaping.
Cheikh Sabaly had a better chance just before the break, but he completely botched a potential tap-in at the far post, instead sending the ball back into the box, and Maxime Colin curled the ball just wide.
The home side continued to spurn chances after the restart, as Risser had to be alert to make a fingertip save to deny Diallo after he was picked out by a pinpoint cross from Giorgi Tsitaishvili.
Metz came even closer from the resultant corner, with Jonathan Gradit producing a heroic goalline clearance to block Jean-Philippe Gbamin’s goalbound effort.
Just when it looked like the game would meander towards a goalless draw, the hosts won a penalty with five minutes to go. Ibou Sané broke in behind the Lens defence before being felled by Saud Abdulhamid, and Hein kept his cool to find the top corner from the subsequent spot-kick.
With a potential nervy ending in store, Hein struck again in injury time to finish a slick counter-attack, and although he was shown a second yellow card for taking his shirt off, he did seal all three points.
It’s a potentially huge win for Metz, who remain at the foot of the table regardless, with an already sizeable margin to safety. Lens’ first defeat in six matches sees them miss the chance to go top of Ligue 1.
Flashscore Man of the Match: Gauthier Hein (Metz)