The Champions League group stage gets under way this week as Liverpool start the defence of the title they won with victory over Tottenham in Madrid.

Here, the PA news agency takes a look at some of the main talking points before the first round of matches.

Liverpool start title defence against familiar faces

European champions Liverpool launch the defence of their title on Tuesday against a familiar foe in Napoli. Carlo Ancelotti's side pushed the Reds all the way in Group C last season and went mightily close to denying them a place in the knockout rounds. The Italians, runners-up to Juventus in Serie A in three of the last four seasons, beat Jurgen Klopp's side 1-0 at the San Paolo Stadium. Mo Salah's solitary goal in the return at Anfield, coupled with a clean sheet, ensured the Merseysiders progressed at their expense – but only after Alisson's brilliant stoppage-time save had denied Arkadiusz Milik.

Tottenham out to go one better than last season's final

Tottenham kick-started their season in time for their return to Champions League action with a convincing win against Crystal Palace at the weekend. Spurs had struggled to get going since their memorable run all the way to the final in May, but they swept away their London rivals and a repeat performance will be needed on Wednesday if they are to launch their European campaign with a crucial win in Athens. Olympiacos came through qualifying unbeaten and have won eight of their nine games in all competitions this season, while Mauricio Pochettino has confirmed he will rotate his line-up.

Manchester City bid to bounce back

The Champions League is the trophy Premier League champions Manchester City covet this season after crashing out of the quarter-finals for the past two years – each time to English opposition. But they gave themselves the worst possible send-off for their trip to tackle the Ukrainian champions with Saturday's shock defeat at Norwich. Pep Guardiola's side, already five points behind Liverpool in the English top flight, are under pressure on all fronts after failing to venture beyond the quarter-finals of this competition for three successive seasons since losing out to Real Madrid in the 2016 semi-finals.

Lampard makes Champions League managerial bow

Frank Lampard, a Champions League winner as a player with Chelsea in 2012, cuts his teeth in the competition for the first time as manager on Tuesday. It appears to be a good time to play Valencia, who surprisingly sacked head coach Marcelino last week after he guided them to successive fourth-placed finishes in his two seasons in charge, while they also beat Barcelona in the Copa del Rey final in May. The Spanish club have won only one of their four LaLiga games this season, while Lampard's young side hit top form against Wolves on Saturday when Tammy Abraham fired in a hat-trick.

Neymar banned as European heavyweights square off in Paris

Neymar was back with a bang for Paris St Germain at the weekend as his stunning added-time overhead kick clinched his side victory over Strasbourg. His winner in his first appearance of the season went some way to silencing the boos from his club's own supporters. But the Brazilian, who failed to seal a move out of Paris this summer after intense speculation, will play no part against one of the clubs he has been linked with due to a three-game European ban for comments he made about the refereeing in his side's round-of-16 defeat to Manchester United last season.