Johannesburg: Arsenal started off their Champion League campaign with a 1-2 defeat at the hands of Dinamo Zagreb in their Group F match at Stadion Maksimir on Wednesday.

Dinamo winger Alex Oxlade-Chamberlain's own goal in 24th minute put his side ahead before Junior Fernandes doubled the lead with the header, Sport24 reported.

Arsenal Striker Olivier Giroud was sent-off before half-time after being shown two yellow cards.

The Gunners scored their first goal when manager Arsene Wenger replaced Oxlade-Chamberlain with forward Theo Walcott.

Walcott managed to score a goal for his side but the home side held on for the win.

Arsenal will next lock horns with Olympiacos on September 30.