Manchester City were in a ruthless mood, as they thumped Feyenoord 4-0 in their Champions League tie.
John Stones opened the scoring after two minutes, before Sergio Aguero doubled the lead in the 10th minute.
Gabriel Jesus netted City's third goal in the 24th minute while Stones rounded off the scoring with his second of the game in the 63rd minute.
Defending champions Real Madrid began their campaign with a convincing 3-0 win over APOEL at the Santiago Bernabeu.
Cristiano Ronaldo bagged a brace on the night, while Sergio Ramos also got on the scoresheet with a fine strike in the 61st minute.
Liverpool had to settle for a point in their opening Group E clash, after they drew 2-2 with Sevilla at Anfield.
The visitors went ahead through Wissam Ben Yedder after five minutes before Liverpool hit back through Roberto Firmino and Mohamed Salah.
Firmino squandered a chance to get a second goal when he missed a penalty before the break. However, Sevilla managed to secure a point thanks to Joaquin Correa's composed finish.
Tottenham Hotspur began their campaign with three points after recording a 3-1 win over Borussia Dortmund at Wembley Stadium.
Spurs went ahead through Heung-Min Son but Dortmund hit back through Andriy Yarmolenko's superb curling effort in the 11th minute.
Harry Kane restored Spurs' lead four minutes later, before he sealed the win with his second goal on the hour mark.
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