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.
Credit for keeping Arsenal at bay should be given to Palace caretaker boss Keith Millen. The 47-year-old, originally from down the road in Croydon, was thrust into the hot-seat on Thursday following the shock departure of Tony Pulis.
So having had less than 48 hours to plan Palace’s assault on their London rivals, Millen’s team did brilliantly to restrict the Gunners for so long.
But their good work came undone in three minutes at the death, when first they were reduced to 10 men when Puncheon went in late on Nacho Monreal, before Ramsey grabbed the winner. The Wales midfielder was quickest to the loose ball after Mathieu Debuchy’s snap-shot had been saved.
Wenger might point to the fact he did not have his full squad available for the opening match as a reason for the below-par display – only five of the many who spent their summer in Brazil started today.
One of those absent was Germany’s World Cup winning defender Per Mertesacker, who might have made a better fist of preventing Hangeland from scoring.
The Norway player, who had not scored in the previous three league season for Fulham, was inexplicably left by Sanchez to roam to the near post to meet Puncheon’s corner.
However, just before half-time, the hero at the other end appeared to lose his bearings as Koscielny sneaked clear to connect with Sanchez’s lofted free-kick.
It was a good Premier League debut for Arsenal’s £35m Chile forward, who worked well out wide in a four-man attacking midfield.
But it was when one of the other players rested, France striker Olivier Giroud, was introduced in the second half that the Gunners looked like a team who could steal the points.
And in the closing seconds, the club’s top scorer last season played a key role when he headed the ball across goal for Debuchy whose shot was saved, only for team-mate Ramsey to tuck in.