In Group E, the focus is definitely at the Mestella, where the clash between Valencia and Chelsea will define the team that will top the group.
An added layer to the battle exists in the form on Juan Mata, who left the Spanish club to join Chelsea over the summer. He was mobbed and given a welcome return upon landing but it remains to be seen if he can complete a happy reunion with three away points for Chelsea.
Starting XIs - Valencia vs Chelsea
Valencia: Diego Alves, Rami, Victor Ruiz, Mathieu, Miguel, Albelda, Banega, Canales, Jordi Alba, Pablo Hernandez, Soldado.
Chelsea: Cech, Cole, David Luiz, Bosingwa, Terry, Ramires, Lampard, Mikel, Malouda, Mata, Torres.
Starting XIs - Bayer Leverkusen vs Genk
Bayer Leverkusen: Leno, Reinartz, Toprak, M. Kadlec, Castro, Rolfes, Bender, Renato Augusto, Sam, Schurrle, Kiessling.
Genk: Koteles, Ngcongca, Simaeys, Nadson, Hubert, Tozser, De Bruyne, Pudil, Vossen, Buffel, Ogunjimi.
Starting XIs - Arsenal vs Olympiacos
Arsenal: Szczesny, Sagna, Mertesacker, Andre Santos, Rosicky, Arteta, Song, Frimpong, Oxlade-Chamberlain, Arshavin, Chamakh.
Olympiacos: Costanzo, Mellberg, Holebas, Marcano, Torossidis, Ibagaza, Fejsa, David Futser, Orbaiz, Djebbour, Mirallas.
Starting XIs - Marseille vs Borussia Dortmund
Marseille: Mandanda, Azpilicueta, N'Koulou, Morel, Diawara, Diarra, Lucho Gonzalez, Kabore, Valbuena, Remy, A. Ayew.
Borussia Dortmund: Weidenfeller, Hummels, Subotic, Piszczek, Schmelzer, Kehl, Gotze, Grosskreutz, Bender, Lewandowski, Kagawa.
Starting XIs - Zenit St Petersburg vs Porto
Zenit St Petersburg: Malafeev, Anyukov, Criscito, Lombaerts, Hubocan, Shirokov, Zyryanov, Fayzulin, Denisov, Danny, Kerzhakov.
Porto: Helton, Alvaro Pereira, Fucile, Rolando, Otamendi, Belluschi, Joao Moutinho, James Rodriguez, Fernando, Kleber, Hulk.
Starting XIs - Shakhtar Donetsk vs APOEL Nicosia
Shakhtar Donetsk: Rybka, Kucher, Rat, Chyzhov, Hubschmann, Jadson, Willian, Alex Teixeira, Srna, Luiz Adriano, Mkhitaryan.
APOEL Nicosia: Chiotis, Paulo Jorge, Jahic, Oliveira, Poursaitides, Nuno Morais, William Boaventura, Manduca, Helio Pinto, Ailton, Trickovski.
Starting XIs - BATE Borisov vs Barcelona
BATE Borisov: Gutor, Bordachev, Filipenko, Simic, Kontsevoi, A. Volodko, Renan Bressan, Olekhnovich, Baga, Rudik, Kezman.
Barcelona: Victor Valdes, Dani Alves, Puyol, Abidal, Xavi, Thiago, Mascherano, Keita, Villa, Messi, Pedro.
Starting XIs - AC Milan vs Viktoria Plzen
AC Milan: Abbiati, Nesta, Abate, Thiago Silva, Antonini, Van Bommel, Seedorf, Nocerino, Emanuelson, Ibrahimovic, Cassano.
Viktoria Plzen: M. Cech, Limbersky, Bystron, Cisovsky, Pilar, Horvath, Petrzela, Jiracek, Kolar, Rajtoral, Bakos.
Bayer Leverkusen host Genk in the other Group E match in hopes that home advantage can help them overcome a disappointing defeat to Chelsea in the previous match.
Arsenal had a stuttering start to the campaign but the Gunners will be looking to build some momentum to get their season going as they play Olympiakos, who traveled across the continent for this Group F match.
Marseille also host Dortmund in Group F, but the French side are missing a few key players in Andre-Pierre Gignac, Stephane M'bia, who are out injured, and Rod Fanni, who is suspended for a red card in the previous match.
In Group G, Porto make the long trip to Russia as they visit Zenit St Petersburg, while Apoel Nicosia travel to Eastern Europe as well when they play Shakhtar Donetsk in Ukraine.
AC Milan recorded their first win of the season in the Serie A last weekend and will be hoping to continue their winning run against Viktoria Plzen in Group H.
Defending champions Barcelona are favourites to come away with three points as they travel to BATE Borisov in the other Group H match, but need to be wary of their poor away record against fairly unknown opponents in the past.
Click here for our Football Match Cast - the one-stop-shop for all true football fans.
Experience live text commentary, team news, starting line-ups, match statistics and player ratings.
Football fanatics can also utilise our Football Live Scores service - every goal, every match and with handy audio goal alerts!
And for those who need to know everything about everything - we proudly bring you the Football Stats Centre.
Champions League Wednesday
Bayer Leverkusen vs Racing Genk
Valencia vs Chelsea
Arsenal vs Olympiakos
Marseille vs Borussia Dortmund
Zenit St Petersburg vs Porto
Shakhtar Donetsk vs APOEL Nicosia
AC Milan vs Viktoria Plzen
BATE Borisov vs Barcelona