Arsenal ran riot as a four-goal blitz in nine first-half minutes helped them rout Lyon 6-0 in the Emirates Cup.
The Premier League side won the Asia Trophy in Singapore last week, and marked their return to the Emirates Stadium with a stylish and fluent performance on Saturday.
Arsene Wenger's men were in complete control and Mesut Ozil's 62nd-minute strike further emphasised their dominance prior to Santi Cazorla rounding off the scoring late on.
Lyon created the first opening of the game when Alexandre Lacazette's delightful flick played in Clinton N'Jie, but Emiliano Martinez was out quickly to make a low save.
Giroud was the first to find the net when he headed Ozil's free-kick into the top left-hand corner, and the Frenchman then turned provider to set Oxlade-Chamberlain clear - the England man coolly slotting past Anthony Lopes.
Iwobi - nephew of former Nigeria star Jay-Jay Okocha - made it 3-0 when he swept home Ramsey's throughball to finish a fine Arsenal move.
The 19-year-old had another goal ruled out for offside shortly after, but Arsenal stretched their lead still further in the 38th minute when Ozil's cross from the left was poked in by Ramsey at the near post.
N'Jie fired a rare Lyon chance wide after the restart, while at the other end Giroud swept a volley wide from Kieran Gibbs' cross.
A fifth did arrive just after the hour, though, more eye-catching football from Arsenal culminating in Ozil drilling into the bottom right-hand corner from the edge of the penalty area.
