Real Madrid and Bayern Munich began their Champions League campaigns with away victories, while Inter Milan crashed to a home defeat to Turkish outsiders Trabzonspor.

Meanwhile last season's losing finalists Manchester United drew 1-1 at Benfica, thanks to a goal from evergreen Ryan Giggs while neighbours Manchester City were held 1-1 at home by Serie A side Napoli.

The biggest upset of the night was in Milan where Ondrej Celustka netted a 76th-minute winner for Trabzonspor - a late replacement for Fenerbahce who were barred over a match-fixing scandal - in a 1-0 victory over 2009/2010 European champions Inter Milan in Group B.

Angel di Maria struck the winner for nine-times European champions Real Madrid in a 1-0 win at Dinamo Zagreb in Group D in which Ajax and Olympique Lyon played out a goalless draw.

Di Maria hit a left-foot shot into the roof of the net in the 53rd minute after taking a pass from Marcelo, who was sent off 20 minutes later for a second booking after taking a dive.

Bayern were 2-0 winners at Spain's Villarreal courtesy of goals in the seventh minute from Toni Kroos and in the 76th from substitute Rafinha.

The win puts Bayern top of Group A where City had to be content with a 1-1 draw with visiting Napoli. Uruguay striker Edinson Cavani struck a 69th-minute opener for the Italians but Aleksandar Kolarov levelled for City with a 75th-minute free-kick.

Manchester City manager Roberto Mancini said Napoli were "very dangerous" on the counter attack.

"We know the Champions League is difficult but we started well and now we must win in Munich in our next game," he said.

French title-holders Lille squandered a 2-0 lead to be held 2-2 by CSKA Moscow in the same group as Trabzonspor and Inter Milan.