Olivier Giroud powered in a stoppage-time header as Chelsea beat Rennes 2-1 to book a place in the last 16 of the UEFA Champions League with two games to spare.
Frank Lampard's side won the reverse fixture 3-0 earlier this month but they were made to work a lot harder for Wednesday's (AEDT) victory - their sixth in a row in all competitions.
Serhou Guirassy looked to have rescued a point for Rennes when he cancelled out Callum Hudson-Odoi's first-half opener in the 85th minute at Roazhon Park.
But second-half substitute Giroud won it in added time to ensure Chelsea will progress from Group E along with Sevilla.
Timo Werner blazed over the crossbar from six yards but Hudson-Odoi, who set up that early chance, soon had Chelsea in front when he controlled Mason Mount's long pass and tucked home after 22 minutes.
Mount should have added his name to the scoresheet seven minutes later, the midfielder thwarted by a superb reaction save from Alfred Gomis.
Chelsea were denied a second when Werner - on target twice from the penalty spot in the reverse fixture - converted Cesar Azpilicueta's cross but was flagged for offside.
Rennes had lost their previous three matches in all competitions without scoring but they managed to find a way past Edouard Mendy, who joined Chelsea from the Ligue 1 side in September.
Mendy did well to save attempts from Gerzino Nyamsi and Guirassy but the latter made the hosts' pressure tell when left all alone to head in.
Just when it looked like Rennes had done enough to frustrate Chelsea, Giroud - on the field for 22 minutes - towered above Nyamsi to score a header of his own after Werner's initial shot was saved.