Arsenal slipped to a shock 2-1 defeat against Dinamo Zagreb in their opening Champions League group stage match.

The Gunners fell behind when Alex Oxlade-Chamberlain turned the ball into his own net after Josip Pivaric's shot was saved by David Ospina.

Olivier Giroud was then sent off for picking up a second booking, before Junior Fernandes headed in from a corner to double Zagreb's lead.

Theo Walcott pulled a goal back when he raced on to Alexis Sanchez's through-ball and slotted in, but the Gunners were unable to find an equaliser as their European campaign began on a losing note.

Here, Sports Mole takes a closer look at the events that unfolded in Croatia.

Match statistics

DINAMO ZAGREB
Shots: 13
On target: 3
Possession: 39%
Corners: 2
Fouls: 14

ARSENAL
Shots: 14
On target: 5
Possession: 61%
Corners: 7
Fouls: 14

Was the result fair?

Zagreb deserved their win this evening against an under-par Arsenal side, who suffered from making so many changes to their starting lineup. The Gunners did made a strong start to the match and Giroud had two decent chances to give them the lead, but it was the hosts who made the breakthrough thanks to an unfortunate own goal from Oxlade-Chamberlain.

The Gunners struggled to respond, and once Giroud was sent off Zagreb took advantage to hit their opponents on the break throughout the second half. Their second goal came from a well-taken corner that was poorly defended by the Gunners, and they clung on nervously to take the points after Walcott's late strike.

Dinamo Zagreb's performance

Dinamo had not won a Champions League match in the group stage for 16 years, but they showed tremendous effort to stun the Gunners this evening. They saw very little of the ball in the opening stages, and were indebted to their keeper for making two outstanding saves.

The game turned in their favour when they took the lead midway through the first half and it provided them with a huge boost of confidence. The dismissal of Giroud also played a huge part, and allowed them to press the Gunners further up the pitch. Having lost 11 of their previous 12 group games, the win will raise their hopes of reaching the knockout stage for the first time in their history.

Arsenal's performance

It was a match to forget for Arsenal, who endured another difficult night in Europe. The Gunners could easily have been a goal or two ahead in the opening minutes, but Giroud saw a header saved by the keeper, before hitting the post soon after. It would prove costly, as Pivaric was allowed far too much space to break clear on goal and see an effort stopped by Ospina, before the rebound cannoned into the net off Oxlade-Chamberlain.

More woeful defending was to blame for the second goal of the evening, as Fernandes broke clear of his marker inside the box to power in a header. Although Walcott came off the bench to pull a goal back, the Gunners could not find a second as their night ended in disappointment.

Sports Mole's man of the match

Eduardo: There were a number of fine displays from the home side, but their goalkeeper takes the plaudits for some crucial saves in the first half. He kept out a header from Giroud that looked destined for the top corner, before getting down quickly to deny the Frenchman again, after the ball had come back off the post. He was also quick off his line and commanded his area well until the final minute.

Biggest gaffe

Giroud must take the blame for his red card this evening. The striker was booked early on for arguing with the referee, before he was sent off for a high challenge on Ivo Pinto. It was a moment of madness from the Frenchman and it ended up costing his team dearly.

Referee performance

There can be no complaints about the display from Ovidiu Hategan, who got all of the big decisions correct. He was right to send off Giroud and he handed out five more deserved bookings throughout the rest of the evening.

What next?

Dinamo Zagreb: Zagreb are back in league action on Saturday with a top-of-the-table clash against Hajduk Split.

Arsenal: The Gunners will look to bounce back when they face London rivals Chelsea at Stamford Bridge on Saturday afternoon.