The Champions League group stage starts this week with Real Madrid looking to win Europe's top club competition for a third straight year, a feat not achieved since Bayern Munich in the 1970s.
Here's a look at the eight groups:
GROUP A (BENFICA, MANCHESTER UNITED, BASEL, CSKA MOSCOW)
Jose Mourinho can be happy with how Manchester United's return after a one-year absence is shaping up, along with his own quest to be the first person to coach three different clubs to European glory. Benfica is a consistent performer in the second tier of Europe's elite; Basel has been weakened by persistent sales of top players since eliminating United in the 2011 groups; and CSKA Moscow finished last in its group in each of the last four seasons — including one that contained United in 2015. After starting the English Premier League with 10 points from a possible 12, the three-time European champion will begin as group favorite.
GROUP B (BAYERN MUNICH, PARIS SAINT-GERMAIN, ANDERLECHT, CELTIC)
Neymar made it his big goal to win the Champions League with Paris Saint-Germain after securing his world-record transfer from Barcelona for 222 million euros ($262 million) in July. Advancing to the knockout stage should be a formality for his new team, which also includes teenage striker Kylian Mbappe in a new-look and exciting forward line. Neymar's first European campaign with PSG will take him to five-time champion Bayern, whose coach Carlo Ancelotti used to manage the French club. Celtic is never an easy team to visit, but the Scottish champions are likely to be fighting it out with Anderlecht for third place.
GROUP C (CHELSEA, ATLETICO MADRID, ROMA, QARABAG)
Qarabag is the first Azerbaijani team to reach this stage and its reward is one of the most competitive groups. Atletico Madrid has reached the final twice in the past three years, losing both times to Real Madrid, while Chelsea — the 2012 European champion — is the current English champion and has recovered after an uncomfortable start to the Premier League. Chelsea and Atletico could be in negotiations over the next few months regarding the sale of Diego Costa, the Chelsea striker who has been estranged in his native Brazil for much of the summer and wants to join former club Atletico.
GROUP D (JUVENTUS, BARCELONA, OLYMPIAKOS, SPORTING)
It will be a major surprise if Juventus and Barcelona, European champions a combined seven times, fail to qualify from the group. They met in the 2015 final, with Barca's prolific front three of Neymar, Lionel Messi and Luis Suarez inspiring a 3-1 win in Berlin. Neymar, of course, is no longer around for Barca, with new signing Ousmane Dembele replacing him. Juventus lost last season's final to Real Madrid and hasn't won the Champions League since 1996. Olympiakos and Sporting are regular qualifiers but rarely advance, with Sporting weakened by the recent sale of midfielder Adrien Silva to Leicester.
GROUP E (SPARTAK MOSCOW, SEVILLA, LIVERPOOL, MARIBOR)
Five-time European champion Liverpool came through the playoffs and gets a chance to avenge its loss to Sevilla in the 2016 Europa League final, which denied the English team a place in last season's Champions League. Spartak, which won the Russian Premier League, is in the group stage for the first time since 2012-13, while Slovenian team Maribor is the big outsider in its third attempt to reach the knockout stage. This will likely be considered the weakest of the eight groups.
GROUP F (SHAKHTAR DONETSK, MANCHESTER CITY, NAPOLI, FEYENOORD)
Pep Guardiola's Manchester City avoided tougher options by being drawn into top-seeded Shakhtar's group. The Ukrainian champion is always fighting against the disadvantage of not playing a real home game in three years due to the conflict involving pro-Russian separatists around its home city. Still, Napoli was one of the more difficult opponents for City from the third-seeded teams and eased past Nice in the playoffs round. Feyenoord returns to the group stage after a 15-year absence and is likely to face a steep learning curve.
GROUP G (MONACO, PORTO, BESIKTAS, LEIPZIG)
Monaco, last season's surprise semifinalist, is the top seed but has been hurt by the departure of key players like Kylian Mbappe, Bernardo Silva and Benjamin Mendy this summer. The French team comes up against Porto in a rematch of the 2004 final won by the Portuguese team. Leipzig didn't even exist then — the club was created in 2009 — and is a newcomer at this level. But the Bundesliga runner-up was the team from the fourth seeds that most of the continent's heavyweights wanted to avoid. Monaco won its group as a fourth-seeded team last season.
GROUP H (REAL MADRID, BORUSSIA DORTMUND, TOTTENHAM, APOEL)
Real Madrid has won the Champions League three times in the past four years, and is looking to become the first team since Bayern Munich (1974-76) to be European champion in three straight years. Madrid's path to the knockout stage may have been smoothed by its fierce rival Barcelona, which weakened Borussia Dortmund by signing Ousmane Dembele. Tottenham will be hoping for better results at its temporary home of Wembley Stadium, where the English team lost two of its three group games last season and hasn't won either of its Premier League games there this season. APOEL famously reached the quarterfinals in 2012 against the odds.