Arsenal striker Yaya Sanogo scored four goals as Benfica were swept aside 5-1 in the Emirates Cup.
The France Under-21 striker did not manage to find the net in any of his 14 appearances last season, having joined from Auxerre on a free transfer.
Sanogo produced a clinical display as he bagged a first-half hat-trick while Costa Rica forward Joel Campbell, back from a loan spell at Olympiacos, also impressed, scoring the other Arsenal goal.
Summer signing Alexis Sanchez was introduced from the bench in the 74th minute for his Arsenal debut.
