After a crushing defeat all but ending any forlorn hopes of a first league title since 1997/98 at the hands of Paris Saint-Germain last time out, Frank Haise needed to galvanise his Lens side as they continued their search of European football.
Without back-to-back league defeats all season and only a solitary defeat on home soil, Lens were never likely to give Monaco an easy task in leapfrogging them in this crunch meeting.
An intense high press approach was clear from the outset and it took less than 10 minutes for the home side to reap the rewards.
Deiver Machado won the ball high up the pitch and perhaps fortuitously, his block tackle rolled into the path of an unmarked Openda.
Seemingly only Alexander Nubel to beat, Openda’s effort was somehow cleared off the line, but only back into the path of the in-form marksman who rolled home and celebrated wildly, albeit after a prolonged VAR check for offside.
Moments later Openda had his second, pulling level with opposing forward Wissam Ben Yedder in the Ligue 1 goalscoring charts, again following fine work down the left from Machado.
The marauding full-back fizzed the ball in across the six-yard box, leaving Openda with an easy finish to allow his side breathing space heading into the break.
Adrien Thomasson thought he had put the home side in an unassailable lead shortly after the break, unmarked as the ball was recycled following a wide free-kick. Despite taking full advantage rifling beyond Nubel, he was belatedly denied by an offside flag.
Philippe Clement’s side were being overwhelmingly outplayed though and it didn’t take long for Thomasson to burst into celebration once more.
Openda’s turn of foot took him beyond the statuesque Monegasque defence, but despite having the opportunity for a third hat-trick of the season, he unselfishly squared the ball for Thomasson to roll home.
It was an uncharacteristic off day for Monaco away from home, summed up by a late miss by Ben Yedder against a team he is yet to taste victory against in eight attempts.
The result ends a run of nine unbeaten away from home for Monaco, with the home side claiming the spoils at the Stade Bollaert-Delelis for the first time in eight meetings.