Reigning European champions Bayern Munich begin their title defence at home to CSKA Moscow on Tuesday, while David Moyes leads Manchester United in the Champions League for the first time.
A look ahead to all eight games on Tuesday, the opening matchday of the 2013-14 UEFA Champions League:
MANCHESTER UNITED V BAYER LEVERKUSEN
The spotlight will be on David Moyes in what will be his first game as a manager in the Champions League proper. His sole previous experience of the competition came in 2005, when Everton lost 4-2 on aggregate to Villarreal in the third qualifying round. He is still getting to grips with life in the United dugout and could do with getting off to a winning start in a testing Group A. Leverkusen qualified for this season's competition by finishing third in the Bundesliga and are coached by a familiar face to Moyes and United fans - Finnish former Liverpool defender Sami Hyypia. His side have started the season well and United supporters will not have forgotten their defeat to the same opponents in the 2002 semi-finals.
REAL SOCIEDAD V SHAKHTAR DONETSK
Appearing in the Champions League for the first time in a decade, Real Sociedad begin their Group A campaign at home to four-time defending Ukrainian champions Shakhtar. Shakhtar have reached the knockout stages in two of the last three seasons but lost a trio of leading players over the summer in full-back Razvan Rat, all-action Brazilian midfielder Fernandinho and the outstanding Henrikh Mkhitaryan. After losing just once in the whole of last season, Mircea Lucescu's side have taken just one point from their last three league games, and went down 3-2 at Karpaty Lviv on Friday. The Spanish side, who have a new coach this season in the inexperienced Jagoba Arrasate, travelled to Levante in La Liga on Saturday.
FC COPENHAGEN V JUVENTUS
Danish champions FC Copenhagen are back in the group stage for the first time since their run to the last 16 in 2010-11 and begin with a daunting home clash against Serie A title-holders Juventus. Stale Solbakken's Copenhagen side had won just one of their opening seven domestic league games before hosting Esbjerg on Saturday but at least in the likes of Olof Mellberg and Daniel Braaten they have players with experience of this level. Mellberg, indeed, played for Juve back in the 2008-09 campaign. Antonio Conte's Juve, faced a trip to Inter on Saturday in the coach's 100th game at the helm, have started the campaign well and are eager to make a major impression in this season's competition after being well beaten by Bayern Munich in the quarter-finals last time around.
GALATASARAY V REAL MADRID
This clash in the heated atmosphere of Istanbul's Ali Sami Yen stadium is a rematch between the clubs, who clashed in last season's quarter-finals, with Madrid winning 5-3 on aggregate. It has been all change in the Spanish capital since then of course, with Carlo Ancelotti replacing Jose Mourinho in the dugout. The Italian has already confirmed that goalkeeper Iker Casillas will come in from the cold to start at the expense of Diego Lopez, while recent big-money signing Gareth Bale will be hoping to feature for the visitors. Defending Turkish champions Galatasaray have had a slow start to their domestic campaign and needed a Didier Drogba equaliser to draw 1-1 at home with Antalyaspor on Friday evening.
BENFICA V ANDERLECHT
Following the trauma of their Europa League final defeat to Chelsea in the spring, Benfica are back in continental competition as they entertain Belgian champions Anderlecht in Lisbon's Estadio da Luz, the stadium which will host this season's final. Jorge Jesus' Benfica side will be hopeful of making an impression in a group that could be one of the most open in this season's Champions League, but they must get off to a good start in a fixture brimming with history. Indeed, these clubs met in the UEFA Cup final in 1983, with Anderlecht beating a Benfica side coached by a certain Sven-Goran Eriksson. Benfica should fancy their chances of recording a win this time, however, against John Van den Brom's side, who are rebuilding after seeing the likes of Lucas Biglia and Dieumerci Mbokani depart over the summer.
OLYMPIACOS V PARIS SAINT-GERMAIN
French champions PSG are the favourites to win Group C as they bid to improve on last season's run to the quarter-finals. They warmed up for their trip to face the Greek title-holders with a 2-0 win at Bordeaux on Friday, achieved without the rested Ezequiel Lavezzi and with record signing Edinson Cavani on the bench for all but the last nine minutes. They can expect to return to the side at the Georgios Karaiskakis Stadium in Piraeus against the three-time defending Greek champions. Coached by former Real Madrid and Spain star Michel, the Olympiacos squad contains numerous players who have previously played in Ligue 1, most notably Javier Saviola, who counts Monaco among his many clubs. PSG coach Laurent Blanc led Bordeaux to victory against Olympiacos in the last 16 in 2009-10.
BAYERN MUNICH V CSKA MOSCOW
Bayern begin their defence of the title with Pep Guardiola - who coached Barcelona to glory in this competition in 2009 and 2011 - now in the dugout. The Bundesliga giants play host to CSKA Moscow, the Russian champions. Bayern come into the game with Mario Gotze, Thiago Alcantara and Javi Martinez all on the injury list and the signs are that last season's all-conquering team are still adjusting to life under Guardiola. Leonid Slutski's CSKA warmed up for their trip to Bavaria with a 1-0 win against Rostov on Saturday, achieved thanks to a Konstantin Bazelyuk goal a minute into his league debut. That left them top of the table and still unbeaten after eight games in their domestic Premier League.
VIKTORIA PLZEN V MANCHESTER CITY
Having failed to progress beyond the group stage in either of the last two seasons, big-spending Manchester City will be expecting to do much better under new coach Manuel Pellegrini, who has taken both Villarreal and Malaga to the latter stages of the competition in recent seasons. Indeed, City failed to win a single match last season, but they have been given a kinder draw this time. This is a fixture that the English club should win, although Pavel Vrba's Plzen have a fine record at their compact Struncovy Sady Stadion and come into the game on the back of a long unbeaten run. City have fitness problems too, with recent recruit Martin Demichelis missing due to injury, and both captain Vincent Kompany and David Silva also struggling.