European champions AC Milan began their Champions League defence with a 2-1 win over Benfica team at the San Siro tonight.
The Rossoneri looked excellent going forward but shaky at the back on occasion and more clinical opponents could have taken something from the game.
As it was, Andrea Pirlo gave them the lead inside 10 minutes with a trademark free-kick into the top corner.
Paraguayan striker Oscar Cardozo hit the post with an open-goal header from two yards out for Benfica and Milan swiftly punished them for the miss.
Kaka led a break which stretched the Benfica defence and last season's Champions League final matchwinner Filippo Inzaghi volleyed home Pirlo's chip across the box.
Nuno Gomes snatched an injury-time consolation strike for Benfica, and the goal meant Shakhtar Donetsk took the early lead in Group D after their 2-0 win over Celtic in Ukraine.
Shakhtar were in control after eight minutes. Defensive errors let in Brandao for the first and Italian striker Cristiano Lucarelli added the second with a spectacular header.
Brandao had a second goal disallowed to give the Hoops hope for the second half, but they could find no way back.
In Liverpool's group, Marseille were 2-0 victors over Besiktas at the Stade Velodrome to go top after the first round of games.
Julien Rodriguez, sent off in Marseille's home defeat to Toulouse in Ligue 1 at the weekend, scored the first after a Samir Nasri corner and former Liverpool striker Djibril Cisse added a late second.
The Reds, last year's beaten finalists, kicked off with a 1-1 draw away to Porto.
Argentina midfielder Lucho Gonzalez - a summer target for Everton - gave Porto an early lead from the penalty spot but Dirk Kuyt quickly levelled up for the Reds with a header from close range.
Valencia lead Group B, featuring Chelsea, after a 1-0 win over Schalke in Gelsenkirchen.
Spain striker David Villa got the only goal for Valencia following good work by Portuguese full-back Miguel.
Chelsea were surprisingly held 1-1 by Rosenborg in a slow start for Jose Mourinho's men.
A devilish ball into the box by Marek Sapara was met on the volley by Miika Koppinen to give the Norwegian side a shock lead at Stamford Bridge.
Andriy Shevchenko showed he is still a Champions League force with the Blues equaliser, heading in a Florent Malouda cross.
Nine-times European champions Real Madrid opened their Group C campaign with a 2-1 win over Werder Bremen at the Bernabeu.
Raul gave the Spanish giants a 16th-minute lead but Werder levelled through Ivorian striker Boubacar Sanogo a minute later.
However, Real were not to be denied and Ruud van Nistelrooy secured the points with his 50th Champions League goal.
Olympiacos and Lazio drew 1-1 in a game played behind closed doors in Greece because of past misdemeanours by the home club's fans.
Argentinian midfielder Luciano Galletti scored a superb goal for the Greek side in the 55th minute, selling the Lazio goalkeeper Marco Ballotta a dummy before tucking the ball into the unguarded net.
But the Roman side levelled when Luciano Zauri's low shot beat Antonis Nikopolidis at his near post.