Coach Jose Mourinho begun his quest for a second successive Champions League title in the best way possible after seeing his Chelsea side beat Paris St Germain 3-0 in their opening Group H match.
But his former team Porto, which he led to glory last May by winning the European title, were the only big club who failed to win on the opening night of the competition proper.
The champions were held to a 0-0 draw by CSKA Moscow in front of their own frustrated fans in their opening Group H match and gave little hint that they could repeat last season's success.
Otherwise, all the big clubs won as expected on Tuesday with Arsenal, Inter Milan, AC Milan, Barcelona and Valencia picking up maximum points.
Chelsea, whose billionaire owner Roman Abramovich has spent over 150 million pounds on new players since buying the club last year, were far too good for PSG in Paris and won 3-0 with two goals from ex-Olympique Marseille hero Didier Drogba and a header from defender John Terry.
Arsenal, who lost two and drew one of their three opening matches in last season's competition, got off to a far better start this time.
They beat PSV Eindhoven 1-0 in their opening Group E match at Highbury thanks to a 42nd minute own goal by PSV's Brazilian defender Alex who turned a Thierry Henry cut-back into his own net.
Panathinaikos beat Rosenborg Trondheim 2-1 in the same group with Argentine Ezequiel Gonzalez scoring both goals after 42 and 79 minutes. Frode Johnsen pulled one back in stoppage time for the Norwegians in front of just 13,000 fans.
AC Milan, European champions two years ago, began their quest for a seventh title with a 1-0 win over Shakhtar Donetsk in Group F in Ukraine with Clarence Seedorf scoring the only goal after 84 minutes.
Shakhtar played for most of the second half with 10 men after Darijo Srna was sent off in the 53rd minute for a second bookable offence.
Barcelona's Henrik Larsson scored against his old club Celtic as Barca overcame a 40-year jinx and beat a Scottish side for the first time since winning against Celtic in 1964-65.
In a match which started 30 minutes late because of crowd congestion, Barcelona were far too strong for the Scottish champions with Deco (20th) and Ludovic Giuly (78th) -- new signings like Larsson this summer -- also scoring.
Chris Sutton gave Celtic a glimmer of hope with a 59th minute equaliser but they were powerless to prevent their three-year 19-match unbeaten home record ending against a better team for which Brazil's Ronaldinho missed a penalty in the 55th.
TOO GOOD
Valencia, UEFA Cup winners and Spanish champions last season, were too good for Belgian champions Anderlecht in their Group G match with Vicente opening the scoring after 17 minutes -- the first goal in this season's group phase -- and Ruben Baraja making it 2-0 just before the interval.
Inter Milan beat German champions Werder Bremen in the same group with drama at the beginning and end of the game.
Werder defender Valerien Ismael was sent off for tripping Adriano after only five minutes -- the joint-fastest dismissal in Champions League history -- but Christian Vieri's ensuing penalty was saved by Werder goalie Andreas Reinke.
It was left to Brazilian Adriano to score from the spot to put Inter 1-0 up after 34 minutes after he was fouled by Frank Baumann and he added the second a minute from time as Inter won 2-0.
Matches in Group A-D will be played on Wednesday.
