Andre Villas-Boas' men need to beat the La Liga side at Stamford Bridge to guarantee progression from Group E, while the Gunners have already qualified for the last 16
We will bring you the team news, fan views, goal flashes, red cards and match reaction - all in one place.
We bring the action to life - from whether Chelsea can ease the pressure on manager Andre Villas-Boas by reaching the last 16 of the competition against Valencia, to how an inexperienced Arsenal side fare away to Olympiakos.
Click on the link below and you can follow all the matches this evening:
As well as bringing you updates from the matches involving the two Premier League clubs, we will keep you up to date with the rest of the Champions League fixtures taking place across Europe, including Barcelona's clash with BATE Borisov.
With reaction coming in from around the continent, we will bring you the best of what the managers and star players have to say on the games within moments of the final whistle.
No matter who you support, you will get all the news and views you need right here throughout the evening.