Monaco's Aymen Abdennour in action with Arsenal's Olivier Giroud durding their Champions League round of 16, first leg soccer match at Emirates Stadium in London, Feb 25, 2015. [Photo/Agencies]

Wenger's Arsenal, who had won eight of their last nine matches in all competitions, flew out of the blocks against his old team, testing the resilience of Monaco's rock-solid defence with a series of early raids.

Giroud went close with a header during Arsenal's opening dominant spell, and then wasted three chances after the break before being substituted, but Monaco weathered the early storm, subduing both the crowd and the home players.

The visitors gradually played their way into the match with winger Anthony Martial and Joao Moutinho looking particularly dangerous, but it was still a surprise when they took the lead through Kondogbia's long-range effort.

There was no real surprise, however, when they doubled their advantage as they were playing the better football when Berbatov's powerful finish ended a swift break.