Laurent Koscielny made it 1-1 just before half-time to draw Arsenal level with manger-less Crystal Palace.
Brede Hangeland had upset the script by heading his team, who saw Tony Pulis quit on the eve of the season, in front at the Emirates.
Making his debut for his new club Hangeland scored from a corner against the run of play after 35 minutes, in a game which Arsenal had been dominating.
However, despite their dominance - Arsenal enjoyed almost 75 per cent possession - the Gunners failed to create any clear-cut chances and had just one shot on target, a long-range Jack Wilshere effort that was easily turned round the post by Julian Speroni.
That was before Laurent Koscielny scored a header of his own, nodding in a free-kick right on the stroke of half-time.
Wenger handed debuts to three players, Mathieu Debuchy, Calum Chambers and Alexis Sanchez who were all solid without being outstanding.
Glenn Moore at the Emirates says:
Parity at the Emirates at half-time due to a brace of set-piece goals, both cleverly glanced in by centre-halves. After 35 minutes of Arsenal dominating without penetrating Brede Hangeland stunned the home support by turning in Jason Puncheon's corner. In first-half injury-time Laurent Koscielny levelled from Alexis Sanchez's free-kick.Reuse content