The Champions League returns this week after a short hiatus, with beaten finalists Paris Saint-Germain looking to get back up and running – and exact a measure of revenge – against Manchester United.
Juventus begin European competition under new head coach Andrea Pirlo, who faces one of the most experienced coaches in the game in Mircea Lucescu.
Barcelona will endeavour to banish memories of August's 8-2 obliteration by Bayern Munich when they face Ferencvaros for the first time, while Chelsea will hope to improve the poor record Premier League teams have had of late against Sevilla.
Here's the key data from Tuesday's matches in Europe's elite competition...
Dynamo Kiev v Juventus: Pirlo feeling the weight of history
Twice a Champions League winner with Milan in 2003 and 2007, Pirlo's first game in the competition comes away to Dynamo Kiev. None of the previous eight Juve head coaches have lost their first match in charge.
In fact, Juve have only been beaten on matchday one in the competition once in 20 previous seasons, winning 11 of those games and drawing eight. That one defeat was a 3-0 loss at Barcelona three years ago.
Dynamo boss Lucescu will be 75 years and 83 days old on Tuesday, making him the oldest coach in Champions League history, overtaking Jupp Heynckes (who was 72 and 357 days old in May 2018). If he wants to celebrate in style, he will need to inflect just a fifth group-stage defeat on Juve in 34 games.
Paris Saint-Germain v Manchester United: Mbappe chasing Messi record
PSG's last home defeat in the competition was that famous loss to United in the 2018-19 round of 16, when Marcus Rashford's late penalty secured a 3-1 win for an understrength Red Devils and sent them through on away goals.
If they are to start their quest for a return to the final with a win, Mbappe might be the man to do it. He has scored 19 goals in the tournament and, at 21 years and 305 days old, he needs just one against United to become the youngest player to reach 20. That would surpass Messi's record, set back in 2010 when he was 22 years and 267 days old.
Of course, if United's unsteady defence focuses on Mbappe, they risk leaving Neymar unchecked. Only Messi (45) had more carries with a take-on in last season's Champions League than Neymar (36), and nobody progressed further with the ball than the Brazil star (1,279 metres).
Barcelona v Ferencvaros: Koeman's worrying numbers
Barca have not lost any of their previous 31 home group games since Rubin Kazan stunned Pep Guardiola's men 2-1 back in October 2009. When you consider Ferencvaros have not been in the competition since 1995-96, when they conceded 19 goals in six matches, you would not expect that Barca run to be stopped.
However, coach Ronald Koeman heads into his first European game in charge with a pretty poor record. The fifth coach to take charge of at least six teams in the competition, after Carlo Ancelotti (eight), Claudio Ranieri (six), Jose Mourinho (six) and Rafael Benitez (six), he has the worst win ratio (26.3 per cent) of anybody to manage at least 50 games in the tournament.
Still, he has Messi. The Barca captain has been involved in at least one goal in 38 of his previous 43 group-stage starts, scoring 56 times and assisting 16.
Chelsea v Sevilla: Can Werner lift English spirits?
Sevilla, who knocked United out of last season's Europa League semi-finals, have won all three major European matches against teams from England. Chelsea, meanwhile, have taken one victory from their previous nine Champions League meetings with teams from Spain, drawing five and losing three.
Frank Lampard will hope Timo Werner can make the difference. The forward was involved in nine goals in his last 11 Champions League games for RB Leipzig (seven scored, two assisted) and could become the third German to score for Chelsea in the competition, after Michael Ballack (four goals) and Andre Schurrle (two). He has, however, never scored at home.
Lazio v Borussia Dortmund:
3 – Dortmund's last Champions League win in Italy was a 1-0 victory over Milan in March 2003, courtesy of a Jan Koller goal. They have lost all three such visits since.
8 – Only Robert Lewandowski (10) scored more group-stage goals last season than Erling Haaland (eight). Haaland averages a goal or assist every 50 minutes in the competition.
RB Leipzig v Istanbul Basaksehir:
6 – Istanbul Basaksehir are the sixth Turkish team to play in the Champions League. Only one of the previous five won their first match – that was Trabzonspor, who beat Inter 1-0 away in September 2011.
14 – RB Leipzig's Hwang Hee-chan created the most chances in open play in the Champions League group stage in 2019-20 (14) when he played for RB Salzburg. He was directly involved in six goals in his six group-stage appearances (three goals, three assists) and was one of two players to both score and assist three goals in the group stage, along with Kylian Mbappe.
Rennes v Krasnodar:
2 – Rennes have lost just twice at home in major European games, winning five and drawing seven of those 14 matches, all of which were in the UEFA Cup/Europa League between November 2007 and December last year.
36 – Krasnodar boss Murad Musayev is 36 years and 345 days old, the second-youngest coach in this season's competition (behind Leipzig's Julian Nagelsmann, 33). He could become the fifth-youngest to win his first game and the youngest since Andre Villas-Boas in September 2011.
Zenit v Club Brugge:
11 – Artem Dzyuba has been directly involved in 11 goals in his 12 Champions League group-stage matches with Zenit (eight goals, three assists). That run includes goals in both games against Belgian side Gent in 2015-16.
19 – Of the 51 teams to have featured in at least 40 Champions League matches, only Steaua Bucharest (9.5 per cent), Dinamo Zagreb (11.9 per cent) and Anderlecht (16.7 per cent) have a lower win percentage than Club Brugge (19 per cent). They have won just eight of 42 matches.