Lyon made it three wins from three with a 3-1 victory over Wolfsburg, star Norwegian striker Ada Hegerberg - the all-time top scorer in the competition - netting twice in the first half before fellow veteran Wendie Renard claimed a third from the penalty spot.
Dutch forward Lineth Beerensteyn claimed a consolation goal for Wolfsburg.
It seemed to have been set up as a good night all round for French clubs.
But there was heartbreak eight minutes into injury time as Real Madrid, through Caroline Weir, claimed a 1-1 draw with Paris FC, who had opened the scoring with a 41st-minute Lorena Azzaro penalty.
Like Lyon, Chelsea remained unbeaten, albeit with one draw in their opening three matches, following a 6-0 thrashing of pointless St Polten of Austria.
Wieke Kaptein opened the scoring in the 13th minute before a quick-fire Catarina Macario double, including a 53rd penalty.
Sam Kerr, on her first start for Blues since December 2023, then claimed her own brace of goals either side of an own goal by St Polten defender Lisa Ebert to make it six in a one-sided contest away from home.
"It feels good. It felt like I had to work myself into it but yeah, happy to score," said Australian Kerr, who is coming back from an knee ACL surgery.
"I'm just happy to be back out here playing in the Champions League again with an amazing team. I'm relishing every moment," she told Disney+.
In the early game, Norwegian side Valerenga, through Stine Brekken, snatched a 1-0 win over Roma, also without a point after three losses from their opening three games.