Arsene Wenger's men were then awarded a penalty in the 15th minute when Alex Oxlade-Chamberlain was brought down inside the box. New signing Lukas Podolski stepped up and made no mistake with his spot kick.
Podolski doubled his personal tally just before half time with a powerful strike that Horn could do nothing about.
Wenger rang the changes at half-time, with only Podolski retaining his first-half place, causing the game to slow down significantly. There was still time for one more Arsenal goal, however, as Gervinho slid an effort inside the near post after breaking down the left flank.
The Gunners will now turn their attention to the Premier League season, with their first match coming away to Sunderland next Saturday.