The Blues are now unbeaten in 13 games in all competitions, their longest run without defeat since November 2018 (18).
It was also the quickest the SW6 outfit have qualified for the Round of 16 stages in 10 years, with two games to spare.
So here’s how Chelsea VAVEL writer Toby Noakes rated Frank Lampard's men tonight...
Edouard Mendy- 7
Didn't have to do a lot but made some important stops when called upon. Still makes every save look easy because of his superb positioning before the opponent lines up their shot.
His calming influence remains refreshing after last season antics. Couldn't do much to save Rennes late equaliser, though.
Cesar Azpilicueta- 6
Trademark performance from the Chelsea captain. Did his job like always, having replaced Reece James who earned a much-needed rest.
Took one for the team late on with the ball smashing into his middle-region (ouch).
Kurt Zouma- 6
Continues to look like the perfect partner for Thiago Silva at the back. Always seemed in control, which was a rarity earlier in the season.
Thiago Silva- 6
Stepped out of defence and looked composed doing so, but was drawn out when Rennes equalised from a corner-kick.
The 36-year-old’s experience will only become more significant as Chelsea continue to progress in the competition.
Ben Chilwell- 6
Two lacks in concentration were fortunately unpunished during Rennes best spell in the first-half. Ben wasn’t his usual energic self going forward but was solid in the tackle.
He could have scored an instant reply to the home sides equaliser after substitute Hakim Ziyech delivered a menacing, but it wasn’t to be.
Mateo Kovavic- 5
An average performance from the Croatian. Didn't break through the lines as he did at the weekend but he wasn’t a liability by any means.
Set the tempo when Chelsea attacked in the first-half though was slow to defend when Rennes broke on the counter. The Italian was strolled past at times.
Mason Mount- 8
Lampard was questioned whether Mount was his son in the pre-match press conference yesterday and with all jokes aside, it's easy to see why such acquisitions are made.
He looks so comfortable as an number eight; dictating play and pressing with confidence. He provided a glorious over the top pass for Callum Hudson-Odoi's goal after wrestling the ball off Jeremy Doku.
Plus he put rising star Eduardo Camavinga on his arse with a outrageous touch and turn, which was nice.
An early contender for Chelsea's, and even England’s, player of the year, maybe?
Callum Hudson-Odoi- 7
Opened the scoring with a delightful goal, finishing cooly passed Alred Gomis in the Rennes net. Didn't look out of place on his unfavoured right-flank and looked sharp despite being only his third start of the season. The England U21 international certainly made the most of his opportunity.
Tammy Abraham- 6
Quieter than he has been in recent weeks but still lead the press well from the front. Was swapped out for veteran Oliver Giroud on 70 minutes, who went on to score the last-gasp winner - which probably earns him a higher rating than his English counterpart (8).
Timo Werner- 5
Looked fatigued to say the least and it came as surprised that he wasn't subbed at half-time, especially with Tottenham on Sunday. The sitter he blazed over the bar early on didn't help his overall rating, either.
N'golo Kante (Mount, 68’)
Giroud (Tammy Abraham, 69’)
Ziyech (Hudson-Odoi, 75’)
Kai Havertz (Kovacic, 76')
James (Werner, 92')