Lille 1 Chelsea 2
Willian’s volley on his 300rd appearance for Chelsea gave them the first win of their Champions League campaign.
Tammy Abraham put them ahead midway through the second half, controlling a great ball from Fiyako Tomori and applying the finish.
Victor Osimhen’s header hauled Lille level 11 minutes later.
But Willian restored their lead with 12 minutes remaining after being picked out by Callum Hudson-Odoi’s left-wing cross.
The fit-again Hudson-Odoi came on as a substitute and Reece James started the game as Chelsea’s youngsters again shone.
But it was seasoned campaigner Willian who got the all-important winner, leaving Chelsea third in Group H after two matches.
Chelsea: Arrizabalaga, Azpilicueta, Zouma, Tomori, James (Hudson-Odoi 67), Kante, Jorginho, Alonso, Willian (Pedro 85), Mount (Kovacic 87), Abraham.
Subs not used: Christensen, Caballero, Giroud, Batshuayi.