Aaron Ramsey struck in added time to hand Arsenal a dramatic 2-1 victory against Crystal Palace in their Premier League opener at the Emirates Stadium.
The hosts were stunned in the 35th minute when Palace new boy Brede Hangeland ran unmarked across the box to glance in Jason Puncheon's corner at the near post.
However, in first-half added time, Laurent Koscielny levelled the match by stooping low to head in Alexis Sanchez's free-kick.
- Man of the match: Aaron Ramsey bailed Arsenal out when they looked destined to flop on the opening day of the season once again.
- Villain: Jon Moss, for completely misunderstanding the concept of vanishing spray when he gave Santi Cazorla a face full in the first half before a free-kick.
- Key moment: Jason Puncheon picking up a second booking late on. Palace were already up against it and his dismissal appeared to galvanise Arsenal for a final push.
- Nick Atkin
Palace - led by caretaker manager Keith Mullen following the shock departure of Tony Pulis - looked set for a well-earned point, but were reduced to 10 men in the dying minutes after Puncheon picked up a second booking late on.
The visitors were then finally undone in the second minute of added time when Ramsey bundled the ball home after Julian Speroni had spilled Mathieu Debuchy's shot straight into his path.
The result sees Wenger's side win their opening league game of the season for the first time in five years.
It had earlier been a positive start by Arsenal, who were without World Cup winning trio Mesut Ozil, Per Mertesacker and Lukas Podolski, all unlikely to be involved until after the midweek Champions League play-off away to Beskitas.
Sanchez, signed from Barcelona, tried his luck when the ball broke to him some 25 yards out, but his long-range chip over Speroni drifted well wide.
The Palace goalkeeper had to be alert on 29 minutes to get down quickly and push a low, curling 18-yard shot from Jack Wilshere behind.
There was a rare moment of panic in the Arsenal rearguard when Wojciech Szczesny's scuffed clearance was driven back towards goal from the halfway line by Marouane Chamakh.
Koscielny was able to get across and block, before Fraizer Campbell's follow-up was put behind.
From the corner, Palace took the lead on 35 minutes. Puncheon floated the corner in from the right, where Hangeland flicked it on at the near post into the far corner.
After being hit against the run of play, Arsenal needed to regroup quickly, and did so as Koscielny levelled just before half-time.
Sanchez was fouled some 35 yards out, and floated a deep free-kick over the Palace defence.
Koscielny ghosted behind the wall of yellow shirts and flicked the ball off the back of his neck into the corner.
Arsenal were forced into a change just after the start of the second half when full-back Kieran Gibbs pulled up with what looked like a hamstring problem and was replaced by Nacho Monreal.
Palace continued to prove difficult to break down, which had been a trademark of Pulis' reign, but also looked dangerous on the counter.
On the hour mark, surprise starter Yaya Sanogo was replaced by Olivier Giroud, the Frenchman having come off the bench at Wembley last weekend to crack home a superb third goal in the Community Shield win over Manchester City.
Arsenal appealed for a penalty when the ball bounced onto Chamakh's arm and chest, but the referee was unmoved.
Chamakh, who had committed a string of fouls all afternoon, was then finally shown a yellow card for clattering into Wilshere on the halfway line.
The midfielder was soon replaced, perhaps as a precaution, by England team-mate Alex Oxlade-Chamberlain with 20 minutes left.
Arsenal had another penalty claim turned away by Moss when Giroud looked to have been pulled down by Hangeland as the ball was swung in from Sanchez.
Giroud flashed an angled drive across the face of goal before, with two minutes left, Puncheon was sent off for a second caution after a late challenge on Monreal.
Arsenal continued to press and were rewarded in the closing moments.
Giroud's knockdown was fired goalwards by Debuchy, signed from Newcastle, and although Speroni produced a fine reaction stop at point-blank range, Ramsey was alert to smash in the rebound and send the Emirates Stadium faithful into wild celebration.