Defending champions Bayern Munich eased back into UEFA Champions League life with a powerful 3-0 win over CSKA Moscow at the Allianz Arena in their opening match in Group D.
David Alaba, Mario Mandzukic and Arjen Robben scored for the Germans who served notice of their intent with a dominant performance on a night when they could have scored more.
Alaba fired the opener from a third minute free-kick and Mandzukic came close twice before making it 2-0 four minutes from the break with a header from Arjen Robben's cross.
Robben made the game safe in the 68th minute when he scored Bayern's third with a superb volley from an Alaba lay-off.
Cristiano Ronaldo scored a hat-trick as Real Madrid made a mockery of the fierce reputation of Istanbul's Ali Sami Yen Stadium with a crushing 6-1 win over Galatasaray in Group B.
Isco hit Real's 33rd minute opener against the run of play but his goal sparked the visitors into life as they added two more from Karim Benzema and Ronaldo's first of the night.
Ronaldo netted his second in the 66th minute from a free-kick taken by Gareth Bale who had arrived as a substitute moments earlier, Benzema made it 5-0 on 81 minutes, and after Umut Bulut had grabbed a late consolation Ronaldo completed his hat-trick in injury time.
In the other Group B fixture, Fabio Quagliarella's 54th minute equaliser salvaged a 1-1 draw for Juventus at FC Copenhagen, who led through Nicolai Jorgensen's 14th minute strike.
Real Sociedad failed to make their early dominance pay in their Group A clash with Shakhtar Donetsk in Spain, and the Ukrainians wound up 2-0 winners with two second half goals from Alex Teixeira.
In Group C, Paris St Germain withstood a bright opening from Olympiakos to run out 4-1 winners in Greece.