AC Milan opened the defense of its Champions League title with a 2-1 victory over Benfica on Tuesday, and Chelsea and 10-man Liverpool settled for 1-1 ties.
Nearly four months after beating Liverpool to win its seventh European Cup, Andrea Pirlo scored one goal and set up the other.
"He is an irreplaceable player,'' Milan coach Carlo Ancelotti said.
Pirlo curled a free kick into the top left corner in the ninth minute. He then passed to Filippo Inzaghi in the 24th, and the striker beat Benfica goalkeeper Quim for his 60th goal in UEFA club competitions -- and 39th in the Champions League.
Inzaghi, who scored twice in the Champions League final and also in Milan's 3-1 European Super Cup win more than Sevilla three weeks ago, is two goals short of Gerd Muller's European record.
Second-half substitute Nuno Gomes tapped in a consolation goal for Benfica in injury time.
The win gives Milan three points in Group D, the same as Shakhtar Donetsk, which beat Celtic 2-0 with goals in the first eight minutes from Brandao and Cristiano Lucarelli.
Chelsea drew 1-1 with Rosenborg, and Liverpool finished 1-1 at FC Porto. Liverpool midfielder Jermaine Pennant was sent off in the 58th minute for a second yellow card.
Real Madrid defeated Werder Bremen 2-1 with a 74th-minute goal from Ruud van Nistelrooy, who also helped set up Raul Gonzalez for the Spanish club's first goal.
Van Nistelrooy's winner was his 50th goal in the Champions League. He slotted in a short pass from Raul to make up for missing a handful of chances in the match.
"The team worked for this win. They knew it wasn't going to be easy,'' Madrid coach Bernd Schuster said. "They worked, they fought, they did some things I liked a lot, some I didn't so much, but we deserved it in the end.''
Also, it was Marseille 2, Besiktas 0; Valencia 1, Schalke 0; and Olympiakos 1, Lazio 1.
On Wednesday, Wayne Rooney returns for Manchester United, which plays at Sporting Lisbon, while Sevilla plays its first game European soccer's elite competition since 1957 at Arsenal and 2006 champion FC Barcelona hosts Lyon.
Also, it's Rangers vs. Stuttgart; AS Roma vs. Dynamo Kiev; PSV Eindhoven vs. CSKA Moscow; Fenerbahce vs. Inter Milan; and Slavia Prague vs. Steaua Bucharest.