Win and Antonio Conte's side would have one foot in the knockout stages. Yes, they have to travel to Rome and host Atlético Madrid at Stamford Bridge, but victory tomorrow night would put Chelsea firmly in charge of Group C with only three games to play.
Lose, however, and the manager who took the Blues to the Premier League title last season would come under increasing pressure. Defeat at Crystal Palace was damaging and came on the back of a loss against title rivals Manchester City. Fail against Roma and questions would be asked of Conte and his players.
It's why the Italian should look back to tackle the future. Chelsea's most complete performance this season came in the Champions League away game at Atlético Madrid; the Blues claimed an impressive 2-1 win thanks to a last-minute winner from Michy Batshuayi.
That night at the Wanda Metropolitano Conte ditched his preferred 3-4-3 system in favour of a 3-5-2 formation that allowed the Blues to domiate midfield, especially in the opening 45 minutes.
Utilising a shape which requires another central midfielder when Chelsea only have two fit and available may sound odd, but it may be the most balanced formation Conte could use without having the energy of Kanté in his side.
Firstly, the formation allows Conte to keep his back three, or back five when out of possession, intact. Who should be included in defence, however, is more of a debate given the indifferent form of David Luiz and Gary Cahill this season.
Against Roma Conte should plump for a back three of César Azpilicueta, Andreas Christensen and Antonio Rüdiger. The Spaniard is Chelsea's best defender, the Dane has excelled in the centre of defence and the German knows Roma's players better than most having left the club in the summer to join the Blues.
And so to the three-man midfield. Against Palace Conte used Cesc Fàbregas and Tiémoué Bakayoko in the middle of the pitch. In theory it should've worked given the former is able to dictate possession from deep and the latter can break up opposition attacks.
Instead the Eagles, through Andros Townsend and Wilfried Zaha, were able to mount attacks with relative ease. With no Kanté Chelsea's midfield lacked mobility and that's exactly why they struggled against the pace and athleticism of Palace's makeshift front two.
To combat this threat it may be wise for Conte to deploy Luiz in midfield. The Brazilian has played the role just the once since returning to the club from PSG in the summer of 2016 but, as discussed here, he can certainly fill in to good effect when necessary.
With Luiz anchoring the midfield and Bakayoko also breaking up opposition forays, Fàbregas would be free to orchestrate Chelsea's attacks safe in the knowledge that his defensive work would be minimal.
Finally, the front two. Against Atleti Eden Hazard played just off of Álvaro Morata and was sublime. It was the Belgian's first start of the season but he showed no signs of ring rust; he was at his creative best and dovetailed expertly with the Spanish frontman.
The free role suits Hazard down to the ground. He is able to drift into pockets of space and then drive at the opposition's defence. At the Wanda Metropolitano, the 26-year-old completed an impressive seven key passes and teed up Morata's equaliser.
That night Hazard also completed seven successful dribbles, which is far more than he averages in the Premier League when he is stationed predominantly on the left of a three-pronged attack (2.2).
So Conte has a decision on his hands. He could stick with the 3-4-3 that turned Chelsea into Premier League champions, but has looked vulnerable without Kanté.
Or he could turn to 3-5-2 which, on paper, offers Chelsea's defence greater protection and also may get the best out of Hazard. It may be an easy choice for the Italian to make.