Giroud off as Arsenal stunned in Zagreb

Making their 18th straight group phase appearance in the competition, the Gunners were hoping to fare better than both Manchester clubs, who lost their opening games on Tuesday, but instead suffered a chastening defeat of their own in their Group F curtain-raiser.

Arsene Wenger's men fell behind on 24 minutes when Alex Oxlade-Chamberlain put through his own net and their troubles were compounded with Olivier Giroud dismissed for a second yellow card just before half-time.

Junior Fernandes added a second for Dinamo just before the hour and although substitute Theo Walcott pulled one back the Croatian champions held on to extend their unbeaten run in all competitions to 42 matches.

"It is not the way we wanted to begin the competition," Wenger told BT Sport.

He added: "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 have enough games to come back. We focus to win our next home game and I'm sure we can beat Zagreb at home."

With an eye on Saturday's Premier League trip to Chelsea and a League Cup tie at Tottenham the following week, Wenger made six changes to the side that beat Stoke 2-0 at the weekend.

Captain Mikel Arteta was handed a first start of the season in midfield with Aaron Ramsey and Francis Coquelin rested while David Ospina deputised for Petr Cech in goal.

Giroud was also restored to the line-up and it was the Frenchman who nearly put Arsenal ahead on nine minutes when he connected with a Santi Cazorla corner only to be denied by an excellent save from Eduardo.

Giroud was then left frustrated by the woodwork after getting on the end of an Oxlade-Chamberlain cross with Eduardo blocking the striker's follow-up effort.

The Arsenal goal had come under little threat aside from two speculative Marko Pjaca strikes but Dinamo made the most of their opportunity when it arrived midway through the first half as El Arabi Hilal Soudani threaded a pass into the path of left-back Josip Pivaric.

Pivaric had crept in behind the visitors' defence and although his initial effort was kept out well by Opsina the rebound ricocheted back off the unfortunate Oxlade-Chamberlain and over the stranded Colombian.

Arsenal's night then lurched from bad to worse as Giroud, cautioned earlier for dissent, was sent off five minutes before the interval after picking up a second booking for a clumsy tackle on Ivo Pinto.

Soudani missed a glorious chance to double the lead for the home side just after the resumption as he headed against the post from close range before stabbing the rebound wide.

Moments after that huge let-off Mesut Ozil found himself alone in front of Eduardo but the German's scuffed shot was smothered by the Dinamo goalkeeper.

A second goal for the home side on 58 minutes eased the nerves at the Stadion Maksimir though.

Mathieu Debuchy made a desperate block to divert a Junior Fernandes effort behind but the Chilean rose above Laurent Koscielny to power home a header from the resulting corner and put Dinamo firmly in control.

Walcott, on the ground where he scored a hat-trick for England against Croatia seven years ago, raced onto a ball through from Alexis Sanchez and steered a composed finish beyond Eduardo to give the Gunners a lifeline on 79 minutes.

Dinamo remained resolute at the back though with Ante Coric nearly netting a third for Zoran Mamic's side right at the death.