Lens moved to the top of Ligue 1 on Friday as Kevin Danso scored the only goal in a 1-0 home win over Troyes.
Franck Haise's side remain unbeaten in their first seven games of the season and now sit one point ahead of reigning champions Paris Saint-Germain, who host Brest on Saturday, and third-placed Marseille.
Lens dominated for long periods but needed Danso's 39th-minute header to see off an obdurate Troyes.
The northern club have not played in Europe since the 2007-08 UEFA Cup.
They finished seventh in the last two seasons after winning promotion in 2020, ending just four points outside the European places in May, and have continued their strong form into the new campaign.
Lens, French champions in 1998, can be overtaken on Saturday by PSG and Marseille, who host Lille.