Arsene Wenger criticised Olivier Giroud after the France international saw red in Arsenal's 2-1 defeat to Dinamo Zagreb in Champions League Group F.
Giroud received two yellow cards in the first half in Zagreb after wasting a number of golden opportunities to give Arsenal an early lead.
His first caution came for dissent after he had been adjudged to have fouled Domagoj Antolic, while the second was brandished for swinging his leg at Ivo Pinto just before the break.
Wenger felt his striker had been unfortunate to receive two bookings for the incidents, but conceded Giroud should have controlled his temper better to avoid the first caution.
"The first yellow for Olivier Giroud is a foul for us and the second is an accident," he told BT Sport. "The first one he was unlucky, but he should not have protested at all.
"They [Dinamo] got away with obvious fouls many times.
"But we have to take it on the chin."
Despite the defeat Wenger remains confident his side can turn their fortunes around in the group, and challenge Bayern Munich for top spot.
He added: "It is not the way we wanted to begin the competition. We were a bit unlucky. We faced a Zagreb team who were committed.
"We gave it all until the end but unfortunately couldn't come back.
"But we have enough games to come back. We focus to win our next home game and I'm sure we can beat Zagreb at home."
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