Champions FC Barcelona begin their bid to become the first side since AC Milan in 1990 to retain Europe's premier club trophy away to Roma while faltering Chelsea host Israelis Maccabi Tel Aviv on the second day of the opening round of Champions League matches.
AFP Sport runs the rule over the eight matches from groups E, F, G and H to be played on Wednesday:
Bayer Leverkusen (GER) v BATE Borisov (BLR)
Bayer Leverkusen and BATE Borisov meet for the first time in their opening Champions League Group E fixture at the BayArena. Leverkusen, who reached the round of 16 last season, advanced to the group stage following a 3-1 aggregate play-off win over Lazio. Difficult to break down on their home ground, Roger Schmidt's side have won five of their last six home fixtures in Europe, and conceded just two goals in their last 12 homes matches. BATE advanced through three qualifying rounds to reach the group stage. It is their fifth group stage appearance but they have never gotten past this round, conceding 24 goals in last year's campaign. BATE's veteran midfielder Aleksandr Hleb knows the German side well however having played them 11 times with German clubs Stuttgart and Wolfsburg.
Roma (ITA) v Barcelona (ESP)
Lionel Messi-powered Barcelona open their title defence in Rome's Stadio Olimpico as they bid to become the first team since AC Milan in 1989 and 1990 to win back-to-back titles. The Spaniards arrive at the former club of coach Luis Enrique buoyed by a hard-fought 2-1 victory at Atletico Madrid in which Messi came off the bench to score the winner to keep their perfect start to the La Liga season at the weekend. No team has ever retained the European Cup in the UEFA Champions League era but Enrique will be looking to get off to a strong start at the club he managed in the 2011-2012 season. Roma warmed up for the tie with a 2-0 win away to Serie A new boys Frosinone at the weekend. The Italians will be looking to put behind them last season's 7-1 home whipping by Bayern Munich at home on their return to the competition after three years.
Dinamo Zagreb (CRO) v Arsenal (ENG)
Dinamo are on a 15-game winless run in the Champions League, failing to make it out of the group stage in four attempts. The Croatian champions came up against Arsenal in the third qualifying round in 2006/2007, losing 5-1 on aggregate to the Premier League giants. Dinamo have found goals hard to come by, mustering only four in their last dozen group outings. Wenger says his side, sitting fourth in the league, need to find the right balance between "urgency and confidence" in Zagreb. Theo Walcott, who scored against Stoke at the weekend, is set to once again be deployed as a central striker rather than in his more usual role as a winger.
Olympiakos (GRE) v Bayern Munich (GER)
Olympiakos, under recently appointed coach Marco Silva, are making their fifth successive appearance in the competition, and have proved tough to dismantle at their Piraeus HQ. The Greeks are on an 11-match unbeaten run in all competitions. Bayern, five-time European champions, welcome back Mario Goetze, the Germany international who is fit after missing Saturday's 2-1 come-from-behind Bundesliga win over Augsburg. But longterm sickbay residents Franck Ribery and Arjen Robben are absent. Coach Pep Guardiola has told his players they must raise their game from their weekend performance to avoid slipping up in Greece. The two sides' only previous encounter dates back to 1980/81 in the European Champion Clubs' Cup with Bayern coming out on top.
Dynamo Kiev (UKR) v Porto (POR)
Returning to the Champions League after missing out for the last two years, Dynamo Kiev aim to defeat a Porto side who are unbeaten in their six visits to Ukraine. Ukrainian double winners Dynamo are competing in the group stage for the 15th time, but manager Seri Rebrov is in charge of a team in the tournament for the first time. Porto, whose manager Julen Lopetegui serves a touchline ban, are looking to improve on last season's run to the quarter-finals where they were defeated by Bayern Munich.
Chelsea (ENG) v Maccabi Tel Aviv (ISR)
With their defence of the Premier League title already in turmoil after three defeats in their first five matches, Chelsea kick off their European campaign hoping for a morale-boosting victory over a Maccabi Tel-Aviv team returning to the competition after a 10-year absence. Condemned to a disappointing Champions League last 16 exit by Paris Saint Germain last season, the west Londoners, reeling after Saturday's 3-1 loss at Everton, will be facing Maccabi for the first time in a competitive fixture, although there are a couple of familiar faces at the Israeli club. Maccabi manager Slavisa Jokanovic, who led Watford to promotion to the Premier League last season, is a former Chelsea midfielder, while defender Tal Ben Haim spent the 2007-08 season at Stamford Bridge.
Valencia (ESP) v Zenit St Petersburg (RUS)
The omens are not good for Zenit in a match that sees two Portuguese former colleagues lead their sides into battle. Valencia's Nuno and Andre Villas-Boas of Zenit worked together under Jose Mourinho in their Porto days when the former was a reserve goalkeeper and the latter a coach. Nuno leads Valencia back into the Champions League after a two-year absence against a side that have lost every time they've played in Spain. Valencia also have four wins and a draw form their home matches against Russian outfits.
Ghent (BEL) v Lyon (FRA)
Hein Vanhaezebrouck's Ghent are perhaps unique in the Champions League as they would have preferred a tougher group. Denied the chance to take on a Barcelona, Bayern Munich or Manchester United, their debut in the competition sees them tackle it with limited ambitions. Managing director Michel Louwagiue says they simply want to get as many points as possible in the group stages to earn as much money as possible. Lyon, semi-finalists in 2010, will be expecting to take three points to boost their chances of a place in the knock-out rounds, although they are missing injured forward Nabil Fekir.