Barcelona, Manchester City and Bayern Munich were all big winners on matchday one of the Champions League.
However, further tests are to come in their second fixtures, with Bayern heading to Atletico Madrid in a particularly tasty face-off - Atleti having beaten the German champions in last season's semi-finals.
Elsewhere, Celtic take on Pep Guardiola and City for the first time, while Rostov make their home debut in Group D.
Using Opta data, we take a look at the best stats ahead of Tuesday's eight group-stage matches.
LUDOGORETS v PSG
- This is the first competitive meeting between Ludogorets and PSG.
- It's also the first meeting between a Bulgarian and French club in the Champions League (since 1992/93).
- Ludogorets have only recorded one win in their seven previous Champions League matches (D2 L4); their sole victory did come at home, however (v Basel, October 2014).
- PSG are currently on a three-game winless run in the Champions League (D2 L1) however, they have only lost three of their last 23 group games in the competition (W16 D4).
- Edinson Cavani's last seven goals in the Champions League for PSG have come at Parc des Princes; he hasn't scored on the road for his club since in October 2014 (v APOEL Nicosia) in the competition.
ARSENAL v BASEL
- This is the first competitive meeting between Arsenal and Basel.
- Arsenal have lost just three of their last 38 home games in the Champions League Group Stages, winning 29 and drawing six.
- Basel have only lost one of their 10 Champions League encounters with English clubs (W4 D5), that was against Manchester Utd at home in November 2002 (1-3).
- Basel are actually unbeaten away from home against English opposition in the Champions League (W1 D4).
- Arsenal have found the net at least twice in their last seven Champions League group games at the Emirates, keeping four clean sheets in that run.
BESIKTAS v DYNAMO KIEV
- Dynamo Kiev and Besiktas have met eight times previously in European competition, with Kiev triumphing five times (D1 L2).
- Besiktas have won just once in their last eight Champions League games (D2 L5), failing to find the net in four of those games.
- The Turkish outfit have lost their last three home games in the competition, their worst ever run in the Champions League/European Cup.
- Dynamo Kiev have only tasted defeat once across their last five matches played away from home in the Champions League (W2 D2).
- Four of the last five Champions League goals scored by Besiktas have come in the 86th minute or later.
NAPOLI v BENFICA
- This is not the first time these teams have played each other; Benfica saw off Napoli by an aggregate score of 4-3 in the UEFA Cup first round during 2008/09.
- Napoli have never lost at home in the European Cup/Champions League (W7 D3).
- Benfica have only won three of their last 17 matches on the road in the Champions League (D5 L9).
- Benfica have won just two of their nine meetings with Italian side in the Champions League/European Cup (D2 L5), and are yet to beat a team from Italy in the Champions League era (D2 L2).
- Arkadiusz Milik has scored three goals in his last three appearances in European competition (Champions League and Europa League).
BORUSSIA MONCHENGLADBACH v BARCELONA
- Borussia Monchengladbach are facing Barcelona for the first time in European competition.
- Barcelona have failed to win their last three matches in Germany (D1 L2).
- The Catalan side are unbeaten in their last five away games played in the Champions League group stage (W3 D2).
- Borussia Monchengladbach have gone 13 home games against Spanish opposition without a clean sheet.
- Against teams from Spain in European competition, Monchengladbach have managed just one victory in their last nine attempts (D2 L6); that win did come in the most recent fixture however (v Sevilla, November 2015).
CELTIC v MANCHESTER CITY
- Celtic and Manchester City have never faced off in European competition before.
- Manchester City will be the second English side Celtic have faced in the Champions League having faced City's rivals Manchester United in the Group Stages in 2006/07 and 2008/09 (W1 D1 L2).
- Celtic will come up against Pep Guardiola for the first time in Europe; despite having faced Barcelona nine times in the Champions League they did not meet during Guardiola's tenure.
- Brendan Rodgers has won just one of his seven Champions League games, with his side scoring five and conceding 16 in those seven matches.
- Sergio Aguero has recorded hat-tricks in his two Champions League appearances this season (including qualifiers).
ATLETICO MADRID v BAYERN MUNICH
- This match is a re-run of the 2015/16 Champions League semi-final; Atletico progressed to the final.
- Atletico Madrid have been involved in four matches versus Bayern Munich in European competition; they have never been able to score more than once across those encounters.
- Diego Simeone's side have kept a clean sheet in 10 of their last 12 group games in the competition, conceding just three goals in total in that run.
- Bayern Munich have won 19 of their last 23 Group Stage games in the Champions League (D1 L3), keeping 13 clean sheets and failing to score just once in that run (0-2 v Arsenal).
- Bayern come into this match having lost three successive Champions League games in Spain; failing to score a single goal in that time.
ROSTOV v PSV EINDHOVEN
- This fixture will be the first time these sides will have ever played each other.
- Rostov have taken on Dutch opposition before, seeing off Ajax in the qualification phase of this season's Champions League (5-2 on aggregate).
- Eindhoven have won just one of their last 13 Champions League games away from home (D3 L9), failing to find the net in eight of those games.
- Rostov have played just three European home games in this millennium, all in Champions League or Europa League qualifying rounds; they are unbeaten in those three games (W1 D2).
- PSV come into this game having claimed just one win in their last five Champions League matches (D3 L1); they are currently on a three-game winless streak (D2 L1) in the competition, failing to score in that time.