Lens edged Strasbourg 1-0 on Saturday to move level on points with Marseille at the top of Ligue 1, while Paul Pogba made his long-awaited return in Monaco's 4-1 loss at Rennes.
Ismaelo Ganiou grabbed the Lens winner midway through the second half before Strasbourg's Valentin Barco was sent off. Lens also finished with 10 men as Morgan Guilavogui saw red in stoppage time.
Marseille, who thrashed Nice 5-1 on Friday, and Lens are a point clear of European champions Paris Saint-Germain. Luis Enrique's side host Le Havre later on Saturday.
Pogba came on as a late substitute for Monaco to make his first appearance in over two years after his career was derailed by injuries, a doping suspension and an extortion case in which he was the victim.
The 2018 World Cup winner failed a drugs test in August 2023 after a match for Juventus and was handed a four-year ban, which was subsequently reduced to 18 months.
Nonetheless, the Italian giants terminated his contract last November, bringing to an early end an unhappy second stint in Turin blighted by injuries and other problems.
In 2024, his brother Mathias was sentenced to three years in prison, with two years suspended, for his role in a plot to extort 13 million euros ($15.3 million) from Pogba in 2022.
But the chance to salvage his career came to the 32-year-old in the form of Monaco, who decided to take a gamble on him once he became available again following the conclusion of his suspension in March.
Monaco have been cautious in their approach to preparing Pogba for a return to competitive action, but coach Sebastien Pocognoli chose to bring on the midfielder in the 85th minute with his team trailing by four goals and down to 10 men.
Abdelhamid Ait Boudlal and Mahdi Camara struck for Rennes before Denis Zakaria was sent off. Breel Embolo added to the lead and Ludovic Blas scored a penalty, with Monaco pulling one back through Mika Biereth after the introduction of Pogba.