Aaron Ramsey scored in stoppage time to break the resolve of Crystal Palace and give title contenders Arsenal a winning start to their league campaign.
Managerless Palace looked set for a point but had forward Jason Puncheon sent off for a second offence in the 89th minute before Ramsey pounced.
The visitors took a shock first-half lead when Brede Hangeland headed in.
The Gunners equalised just before the break when Laurent Koscielny nodded home from Alexis Sanchez’s free-kick.
Despite kicking off their Premier League challenge with a win, it was an inauspicious start having barely made Palace keeper Julian Speroni work for his wage.
Apart from the two goals, the only other time the Palace stopper was called to save his team was when he pushed away Jack Wilshere’s drive in the first half.