West Brom striker Robert Earnshaw came off the bench to earn his side a battling draw at Arsenal.
The Gunners dominated for much of the game, with Pascal Cygan, Thierry Henry and Patrick Vieira all going close.
They looked headed for victory courtesy of a dreadful error by West Brom keeper Russell Hoult, who allowed Robert Pires' shot through his fingers.
But Earnshaw got between two Arsenal defenders to poke home Jonathan Greening's cross and earn the point.
West Brom went into the game without an away win all season, while Arsenal had not lost a league game on home turf for 27 games.
And it was not long before the Gunners were into their stride.
Henry played a one-two with Vieira and then connected perfectly with a powerful shot that was blocked by the considerable presence of Darren Moore.
Cesc Fabregas almost caught out Hoult with a floated effort that looked headed for the top corner but the keeper was able to backtrack and collect.
The champions were not at their fluent best but they continued to create chances and Moore again came to West Brom's rescue with a sliding block tackle to cut out Pires' low shot.
It looked only a matter of time before Arsenal got the breakthrough.
Vieira saw a free header saved comfortably by Hoult and then Fabregas took the ball off the head of Kolo Toure, who looked certain to score from a Pires corner.
West Brom remained dangerous on the counter attack with Neil Clement whipping in a cross that Andy Johnson was close to getting on the end with a diving header.
The ball travelled between Ashley Cole and Cygan, and Zoltan Gera was left free at the back post but could only fire into the side netting with Jens Lehmann well beaten.
Arsenal enjoyed another spell of pressure shortly before half-time with Cygan's header deflecting off Clement but Hoult reacted well to block.
Henry, who had been kept relatively quiet, curled a 30-yard free-kick towards the bottom corner only for Hoult to pull off a fine one-handed save.
Shortly after the restart, Henry ghosted by two men down the left wing, before setting up Pires for a shot that looked destined for the net only for Cole to get in the way.
But the Gunners got the breakthrough nine minutes after the break, courtesy of Hoult's mistake.
Pires ran at the Albion defence before curling a shot that Hoult appeared to have collected, but somehow he allowed the ball to slip through his hands and into the bottom corner.
Henry could have added a second but after evading several challenges he completely missed the ball from 10 yards out.
Cygan missed an even easier chance when he was picked out beautifully by Bergkamp, but the defender demonstrated why he is largely employed at the other end of the field by heading over the top.
Then from nowhere, the Baggies produced an equaliser when Greening sent in a pinpoint cross from the right and Earnshaw stole in to fire home.
The goal seemed to knock the stuffing out of Arsenal, who threw on Jose Reyes and Robin van Persie.
But apart from an off-target header from Vieira, they failed to threaten in the latter stages and manager Arsene Wenger will no doubt be concerned at yet more dropped points at home.
Arsenal: Lehmann, Lauren, Toure, Cygan, Cole, Ljungberg, Vieira, Fabregas (Reyes 81), Pires, Bergkamp (Van Persie 88), Henry.
Subs Not Used: Senderos, Almunia, Hoyte.
Goals: Pires 54.
West Brom: Hoult, Scimeca, Moore, Purse, Clement, Contra (Earnshaw 75), Greening, Johnson, Sakiri (Gaardsoe 84), Gera, Kanu (Horsfield 75).
Subs Not Used: Haas, Kuszczak.
Goals: Earnshaw 79.
Ref: H Webb (S Yorkshire).