Real Madrid got their Champions League title defence off to a strong start on Wednesday by convincingly beating AS Roma 3-0 at home with goals from Isco, Gareth Bale and a stoppage-time strike from returning striker Mariano Diaz.
In other matches on Wednesday night, Juventus beat Valencia 2-0, Bayern Munich beat Benfica 2-0, CSK Moscow and Plezen drew 2-2, Lyon beat Manchester City 2-1, and Manchester United beat Young Boys 3-0.
Julen Lopetegui's Real Madrid, who won the last three editions of the competition, made a flying start against last season's semi-finalists Roma, but took their time to make their dominance count.
Isco, Bale, Sergio Ramos and Dani Carvajal all missed relatively simple chances for the hosts, who were not far from going behind when Turkish youngster Cengiz Under darted in behind the defence but sent his finish flying wide.
It took a wonderfully struck free kick from Isco right at the end of the first half for Real to take a deserved lead, and their dominance continued in the second half.
Bale saw a deflected shot bounce off the crossbar shortly after the interval but got the goal he craved not long after, racing on to a raking pass from former Tottenham Hotspur team mate Luka Modric and arrowing in off the post in the 58th minute.
Roma did not completely wilt after conceding again and it took an impressive save from Keylor Navas to deny the lively Under, as the Costa Rican goalkeeper justified his inclusion in the team after briefly losing his place to Thibaut Courtois.
Roma goalkeeper Robin Olsen did his best to keep the scoreline dignified by denying Isco and Marco Asensio but was powerless to stop Mariano.
The striker was playing his first game after returning to Madrid from Olympique Lyonnais and got the crowd on their feet with a wonderful curling strike into the top corner.
Real lead Champions League Group G with three points after Viktoria Plzen blew a two-goal lead to draw 2-2 at home to CSKA Moscow, who equalised in the 95th minute with a converted penalty from Croatian striker Nikola Vlasic.
Manchester City suffer surprise home loss to Lyon
Manchester City looked far from potential Champions League winners as they fell to a surprise 2-1 loss at home to Olympique Lyonnais on Wednesday with a flat performance leaving them with plenty of work to do to progress from Group F.
The Premier League champions, favourites with some bookmakers to win Europe's top club competition this season, were well below their best throughout and now face a serious challenge to progress from a group which also features Germany's Hoffenheim and Ukraine's Shakhtar Donetsk.
City manager Pep Guardiola, serving a suspension, was forced to watch the game from the stands as his assistant Mikel Arteta took charge and it was a frustrating night for the pair, whose side have now lost four games in a row in the Champions League.
In contrast to a flat-looking City, Bruno Genesio's Lyon delivered a tactically superb display, defending in numbers to nullify City's normally dangerous forward line and then counter-attacking at pace.
The visitors took the lead in the 26th minute through Maxwel Cornet, who drove home after Fabian Delph made a hash of clearing a Nabil Fekir cross from the left.
Gabriel Jesus, City's Brazilian striker, had a strong appeal for a penalty turned down but that was one of the few moments in which he really threatened in the box.
Ilkay Gundogan had an effort disallowed after Italian referee Daniele Orsato ruled that Raheem Sterling was offside but City's frustrations in attack were not their only problems.
Fekir, who was strongly linked with a move to City's Premier League rivals Liverpool in the close season, then made it 2-0 to the French side in the 43rd minute, bursting clear and beating Ederson with a low drive after Fernandinho had given up possession in midfield.
It could even have been 3-0 when Memphis Depay hit the post on the hour after a magnificent through ball from Tanguy Ndombele but after that let-off City earned themselves a lifeline through Bernardo Silva, who produced a smart finish after a superb jinking run from substitute Leroy Sane.
City's attempts to get an equaliser, however, were foiled by a combination of a well-drilled Lyon defence, which kept chances to a minimum, goalkeeper Anthony Lopes, who produced a fine save to deny substitute Sergio Aguero and some poor decision-making from City's forwards.
The defeat was a fourth straight Champions League disappointment for City, who lost both legs of last season's quarter-final against Liverpool and the second leg of their last-16 clash against Basel.
"Really disappointing. To concede two goals like we did is very frustrating," said City defender John Stones. "We came in at halftime a bit deflated. We picked ourselves up and played a better second half but it was frustrating."