Substitute Olivier Giroud's last-minute header gave Chelsea a 2-1 victory in Rennes which sees them qualify for the last 16 of the Champions League.
In a game of shifting momentum, Chelsea dominated early and only Timo Werner will know how he skied over the bar from inside the six-yard box in the third minute.
Chelsea went in front when Mason Mount's wonderful 50-yard ball perfectly set up Callum Hudson-Odoi who calmly finished to put his side in front.
After surviving a period of pressure at the end of the first half it seemed that Chelsea would hold out fairly comfortably in the closing stages before Sehrou Guirassy's bullet header five minutes from time.
But Giroud scored in injury-time to secure Chelsea's place in the next round.