Arsenal manager Arsene Wenger has insisted that his side were unlucky to lose to Dinamo Zagreb in their opening Champions League match and highlighted the decision to send off Olivier Giroud as a turning point.

The Gunners had already gone a goal down after Alex Oxlade-Chamberlain's own goal when Giroud was shown a second yellow card before half time for catching Ivo Pinto after he had already been booked for dissent.

Wenger praised the effort of his side but questioned the referee's decision to dismiss the French striker.

"It is not the way we wanted to begin the competition," he told BT Sport. "We were a bit unlucky. We faced a Zagreb team who were committed.

"The first yellow for Olivier Giroud is a foul for us and the second is an accident. They got away with obvious fouls many times.

"We gave it all until the end but unfortunately could not come back. We have enough games, we focus to win our next home game and I am sure that we can beat Zagreb at home."

Arsenal must now travel to Stamford Bridge in Saturday's early kickoff to face Premier League champions Chelsea.