Arsene Wenger was left frustrated after seeing his side held to a draw at West Brom.
Claudio Yacob's near-post header put the home side in front with three minutes until half-time, before Jack Wilshere levelled with a strike from outside the box.
The Gunners return to the top of the league level on points with Liverpool, but with rivals Tottenham losing could view the game as a missed opportunity.
But it was an excellent result for West Brom, who went ahead with a well-worked goal.
The Gunners failed to clear a corner and allowed Morgan Amalfitano to send a vicious cross in from the right.
Yacob, free in the six-yard box, directed a near-post past Wojciech Szczesny to put West Brom ahead and that's how it stayed at the break.
The Baggies continued to frustrate Arsenal, but Jack Wilshere's deflected strike rescued a point for the visitors.
The Baggies, fresh from downing Manchester United last weekend, began the match positively, Saido Berahino combining well with Stephane Sessegnon on his full league debut to free Liam Ridgewell on the left and earn an early corner.
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Arsenal cleared the set-piece well and might have had a good break on their hands had the ball fallen to someone quicker than Olivier Giroud.
A deflection almost put the hosts ahead just before the quarter hour mark, Berahino's shot changing course via Mathieu Flamini's leg and needing swift reactions from Wojciech Szczesny.
West Brom gradually took control of the midfield, Yacob and Youssuf Mulumbu proving an effective double act in the central area.
Wilshere was having less joy but came to the fore in 24th minute when he made a neat one-two with Giroud before sending a first-time shot a yard wide.
England manager Roy Hodgson's heart would have been in his mouth when Wilshere hit the deck and stayed there soon after, but his problem proved no worse than an accidental poke in the eye from Yacob.
West Brom were aggrieved when Sessegnon was blocked as he looked to skip between Mikel Arteta and Kieran Gibbs and nothing was given, though contact did appear to be just outside the penalty area.
Aaron Ramsey, so prolific this season, went close when his low shot through a packed box was well saved by Boaz Myhill but West Brom were enjoying much more of the ball.
Their pressure paid three minutes from the break. Amalfitano's initial corner was cleared but Mulumbu produced a sublime piece of control and fed the ball straight back to him. The Frenchman produced a killer cross which Yacob nodded home at the near post/
There was still time before the whistle for Mulumbu to give Wilshere the runaround with another skilful piece of footwork.
The second half began explosively, with wonderful chances at both ends inside the first three minutes.
The Baggies went first, Berahino galloping forward and making 30 yards before looking for Nicolas Anelka at the far post.
The pass seemed perfect but Anelka made a mess of his finish and got the ball trapped between his feet.
Moments later Arsenal advanced, with Giroud's lay-off finding Wilshere 10 yards out only for a wayward finish to spare West Brom.
The pace barely slowed before Anelka went even closer. Ridgewell took advantage of a yawning gap on Arsenal's right flank to play in the veteran, who moved towards goal and opened his body only to sidefoot wide of the far post.
Arsenal had a penalty appeal for handball waved away when a Gibbs cross was blocked by Billy Jones, but the full-back appeared to do everything he could to withdraw his arm.
They were level after 63 minutes, with Wilshere the scorer. Ozil and Giroud were the instigators, with the latter rolling the ball to substitute Tomas Rosicky on the edge of the box.
His one-touch pass sat up for Wilshere, who did not hesitate in unleashing a left-footed shot from 20 yards. A deflection off Jonas Olsson turned a decent looking effort into an unstoppable one.
Arsenal were buoyed and probably should have taken the lead when a cute chip from Ozil presented Giroud with a delicious chance to volley from 10 yards. He snatched at the shot, though, leaving Ozil to shake his head.
Giroud's struggles continued when a rejuvenated Wilshere picked him out with a glorious ball over the top. This time the combination of a heavy first touch and a brave smothering save by Myhill denied him.
Jones saw a 25-yarder well saved by Szczesny, but it appeared Arsenal's game to win. Wilshere thought he had a spot-kick when Mulumbu careered into him from behind, but the officials did not agree.
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Source: Mirror Uk
