The 20th edition of the UEFA Champions League kicks off this week with a round of matches that features two mouthwatering clashes between four past winners. Barcelona face AC Milan on Tuesday, while Benfica host Manchester United on Wednesday.

With the exception of Juventus and Liverpool, all of European football’s heavyweights will take part in this special anniversary edition of the competition. Meanwhile, five clubs – Manchester City, Napoli, Trabzonspor, Otelul Galati and Viktoria Plzen – will all be appearing for the very first time.

The group phase of the competition runs until 7 December, with the final to be held on 19 May 2012 at the Allianz Arena in Munich.

The big game
Barcelona - AC Milan, Group H, 13 September 2011, Camp Nou, Barcelona

Tuesday’s match between Barcelona and AC Milan, who are both three-time winners and reigning champions of Spain and Italy respectively, will be the pair’s twelfth meeting. Zlatan Ibrahimovic has unfortunately been ruled out of the clash due to an injury, and will not get a chance to cross swords with Blaugrana boss Pep Guardiola. However, the tie should still be fiercely contested. 

The teams have four wins and three draws apiece from their past 11 encounters, but a victory would nonetheless be sweet revenge for Barcelona, who are still smarting from their 4-0 defeat in the 1994 final. Alexis Sanchez has been ruled out for two months and will not feature for the Catalans, while AC Milan will be without Gennaro Gattuso, who is serving a five-match ban.

Group A (Wednesday 14 September)
Villarreal - Bayern Munich
Manchester City Napoli

Group A has been labelled the ‘group of death’ in some quarters, and all four sides will be aware of the dangers of dropping points at home. Villarreal, still relatively new to the competition, face a stern test against in-form Bayern Munich and the prolific Mario Gomez. The striker has racked up eight goals in his last five outings, including four in Bayern’s recent 7-0 victory over Freiburg. Manchester City have also been red-hot in front of goal, with forwards Sergio Aguero and Edin Dzeko netting a combined total of 12 goals in four matches. However, manager Roberto Mancini will be wary of resurgent, South American-tinged Napoli, who began their Serie A campaign with a 3-1 away victory against Cesena.

Group B (Wednesday 14 September)
Inter Milan - Trabzonspor
Lille - CSKA Moscow

Inter Milan kick off their Champions League campaign at home to debutants Trabzonspor, who joined the competition as late replacements for Fenerbahce. The Italians will be without new signing Diego Forlan, however, as he is ineligible for the group phase. French champions Lille will be hoping Belgian star Eden Hazard can fire them to a winning start against CSKA Moscow, in a match that will no doubt be crucial in the battle for second place.

Group C (Wednesday 14 September)
Benfica - Manchester United
Basel - Otelul Galati

Forty-three years after Sir Bobby Charlton’s brace sealed their emphatic victory over Benfica in the European Cup final, Manchester United face the Portuguese side once again. United have made a prolific start to the new Premier League campaign, averaging 4.5 goals per match thanks in no small part to the outstanding form of Wayne Rooney. The forward has linked up well with wide-man Nani, who will no doubt relish the return to his native Portugal. Basel face Otelul Galati in the group’s other fixture, with the latter recently crowned champions of Romania for the first time in their 47-year history.

Group D (Wednesday 14 September)
Ajax - Lyon
Dinamo Zagreb - Real Madrid

Dinamo Zagreb return to Champions League action 12 years after their debut appearance, having beaten Malmo in the qualifying play-offs. The Croatians face a tough start to the group, as they host Spanish giants Real Madrid. Ajax face Lyon in the other match in Group D, and there will be a sense of déjà-vu for both sides. The pair met at the Amsterdam Arena at the same stage of the competition nine years ago, a match that Ajax won 2-1.

Group E (Tuesday 13 September)
Chelsea - Bayer Leverkusen
Racing Genk - Valencia

Former Chelsea favourite Michael Ballack returns to Stamford Bridge with Bayer Leverkusen, who, with just two victories from 15 matches, do not have the best record on English soil. Chelsea have topped their first-round group six times out of eight, and new manager Andre Villas-Boas will be keen to add to that record. Genk also have a new boss in the shape of Mario Been, who appears unfazed by the prospect of hosting Valencia. He has also made no secret of his gameplan, declaring: “I am a coach who looks to attack and dominate opponents”.

Group F (Tuesday 13 September)
Olympiacos - Marseille
Borussia Dortmund - Arsenal

Borussia Dortmund and Arsenal find themselves in the same boat ahead of Tuesday’s Group F encounter. Both are short on confidence, and both will be looking for a convincing victory to provide a measure of reassurance. The situation is even more delicate for Marseille, who travel to Greece to take on Olympiacos. The French outfit have made a dismal start to the new season, failing to win any of their first five matches in Ligue 1.

Group G (Tuesday 13 September)
FC Porto - Shakhtar Donetsk
APOEL Nicosia - Zenit St Petersburg

The main event in Group G sees two recent UEFA Europa League champions go head-to-head. Porto and Shakhtar Donetsk won the competition in 2011 and 2009 respectively, and the pair are strong contenders to secure the group’s two qualifying berths. Meanwhile, Zenit St Petersburg are away to APOEL Nicosia, who will no doubt be keen to showcase the positive progress of Cypriot football.

Group H (Tuesday 13 September)
Barcelona - AC Milan
Viktoria Plzen - BATE Borisov

Holders Barcelona face fellow group giants AC Milan, while plucky first-time qualifiers Viktoria Plzen and the more experienced BATE Borisov will both be looking for a positive start to the tournament.

Player to watch
Mikel Arteta faces a somewhat daunting challenge at Arsenal. The 29-year-old is charged with becoming a leader in a team under reconstruction, and has the responsibility of taking over playmaking duties from the departed duo of Cesc Fabregas and Samir Nasri. Arteta came through the youth ranks at Barcelona and had spells at Paris Saint-Germain, Rangers and Real Sociedad – the club he supported as a child – before spending six seasons with Everton. Arsene Wenger will be looking to the midfielder to be Arsenal's attacking hub this season, and to guide a side full of ambition but still lacking in experience.

The stat
The number of past Champions League winners that have qualified for the 20th edition of the competition. They are: Marseille; AC Milan; Ajax; Borussia Dortmund; Real Madrid; Manchester United; Bayern Munich; Porto; Inter Milan and current holders Barcelona.

The words
“When a player hears the (Champions League) anthem before a match, he fills with adrenaline because he knows there’s nothing better. The Champions League is the pinnacle for a player, and the highest level there is. The players are fully motivated whether they’re up against Manchester United or Basel,” Benfica manager Jorge Jesus.

Have your say
Will Barcelona become the first team to win back-to-back Champions League titles?