Matchday one of this season’s Champions League continues on Wednesday with Bayern Munich and Manchester City locking horns in a crunch Group E tie at the Allianz Arena.
Man City were given a potential boost by the news that Bayern Munich stars Arjen Robben and Franck Ribery are doubtful through injury but English champions City will be without influential defender Pablo Zabaleta, who is suspended.
Roma and CSKA Moscow complete Group E’s first round fixtures with the pair meeting in Italy.
In group F Luis Enrique makes his competition debut as Barcelona coach when the Catalans hosts Cypriot club APOEL at the Camp Nou.
Barcelona will look to continue their fine start to the season which has seen them win all three of their domestic league matches to sit top of La Liga.
Having lost only one of their last 27 Champions League matches at home Barca will fancy their chances of kick-starting their European campaign on a winning note.
Ajax host Paris Saint Germain in the other Group F tie.
Chelsea are overwhelming favourites to finish top of a relatively easy Group G. They begin their charge for European glory with a home game against the Germans of Schalke.
The Blues have made a blistering start to the season with four straight Premier League wins and with red hot striker in Diego Costa in devastating form, confidence of an opening day victory for Jose Mourinho and his men will be very high.
In the other Group G encounter a struggling Sporting Lisbon travel to Slovenian to face NK Maribor who beat Celtic in the playoffs to reach the group stage proper for the first time in 15 years.
In Group H, Porto entertain the Belarusians of BATE Borisov who are in the group stages for the third time in four seasons, but have never qualified for knockout action.
Match favourites and 2004 champions Porto could be boosted by the return of influential defender Alex Sandro from a thigh strain suffered last month but will still be missing a host of key players through injury – on-loan Barcelona forward Cristian Tello, teenage midfielder Oliver Torres and forward Goncalo Paciencia among those on the injury list.
Group H also sees Athletic Bilbao, who making their first appearance in the tournament since 1998, host Shakhtar Donetsk.