Allan Saint-Maximin has joined Lens after leaving Mexican giants Club America.
Former Newcastle United winger Saint-Maximin left Club America in the past few days, reportedly due to his family receiving racist abuse.
He has now signed on at Lens, who have been a surprise package in Ligue 1 this season.
They sit second in the table, just two points behind Paris Saint-Germain, and recently went on a 10-game winning run in the competition.
Monaco are enduring a more difficult campaign domestically and sit 10th in the standings.
However, they have progressed into the Champions League knockout stage play-offs – they will face PSG over two legs later this month.
And they will have a new winger on board for those ties, with Simon Adingra completing a loan move from Sunderland.
Adingra only joined Sunderland from Brighton last summer, but failed to establish himself in Regis Le Bris' starting XI.
The 24-year-old scored just one Premier League goal for the Black Cats. Monaco's loan agreement includes an option to buy.