Bayer Leverkusen are hoping to capitalise on the absence of Barcelona superstar Lionel Messi when they face the Spanish side at the Nou Camp on Tuesday.
Messi, who scored a total of 60 goals and set up 28 more in 60 appearances to help Barca capture a Primera Division, Champions League and Copa del Rey treble last season, hurt his left knee in Saturday's 2-1 win against Las Palmas and will be sidelined for two months.
Barca, who began their Champions League title defence with a 1-1 draw at Roma in their pool opener, have reason to be confident.
Since losing 3-0 to Bayern Munich in May 2013, Barca are unbeaten at home in the competition, winning their last six games at the Nou Camp.
Bayer, who thumped BATE Borisov in their group opener 4-1 at the BayArena, warmed up for the trip to Spain with a 3-0 triumph at Werder Bremen on Saturday.
The victory, their biggest in the domestic campaign this season, lifted Roger Schmidt's side to fifth in the Bundesliga standings, nine points adrift of league leaders Bayern Munich.
Barca have beaten Leverkusen in their previous five meetings.
Jose Mourinho returns to his former club Porto as Chelsea look to make it two wins from two in the Champions League on Tuesday night.
The Blues boss enjoyed great success with the Portuguese giants, leading them to UEFA Cup success in 2003 before masterminding their Champions League triumph the following season.
While Chelsea eased to a 4-0 win over Maccabi Tel Aviv in their opening Group G fixture, Porto had to settle for a point away to Dynamo Kiev after conceding an 89th-minute equaliser.
The sides last met in the group phase of this competition in 2009, Nicholas Anelka scoring the winner for Carlo Ancelotti's Chelsea in the meeting at the Estádio do Dragao.
Arsenal take on Olympiakos at the Emirates on Tuesday looking for a win to get their Champions League campaign back on track.
Arsene Wenger's side slipped to a 2-1 defeat to Dinamo Zagreb in their first match with Olivier Giroud sent off towards the end of the first-half.
It was a far from ideal start but the Gunners will hope to start making amends with victory over an Olympiakos side that suffered a 3-0 home defeat to Bayern Munich in their opening fixture.
The return to goalscoring form of Alexis Sanchez is undoubtedly a boost for Arsenal while Theo Walcott, who is set to start up front with Giroud suspended, should be confident, having also got himself on the scoresheet in the 5-2 win over Leicester.
Bayern Munich have just "14 or 15" fit players for Tuesday's Champions League home game with Dinamo Zagreb, says boss Pep Guardiola.
Midfielders Arturo Vidal, a Copa America winner with Chile this summer, and Sebastian Rode are the latest players to receive treatment.
Vidal is nursing a knee problem while Rode has had treatment for a knock.
Bayern are already without wingers Arjen Robben and long-term absentee Franck Ribery as well as defenders Medhi Benatia and Holger Badstuber.
Midfielder Javi Martinez only recently came back from a four-week injury break.
Bayern, five-time champions of Europe, have won all seven Bundesliga fixtures this season.
The German champions won 3-0 in Greece against Olympiakos in their opening Champions League Group F game.
Dinamo Zagreb, champions of Croatia 10 years running, are unbeaten in their last 45 matches in all competitions, a run stretching back to November 2014.
Valencia have only one thing in mind heading into Champions League action on Tuesday and that is to win at Olympique Lyon.
The sides will square off at the Stade de Gerland in Group H and the players in the Spanish outfit believe that after falling in their opener at home to Zenit St Petersburg, they must collect three points to have a realistic chance of progressing in the competition.
Valencia began their group campaign with a 3-2 home defeat to the Russian team, a result that has the Spaniards at the bottom of the pool.
Lyon, who are playing in the group stages of the competition for the first time since 2011, lost 3-1 at Girondins Bordeaux on Saturday.
It was their second loss in Ligue 1 and left them in eighth place in the standings, eight points adrift of league leaders Paris St Germain.
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