Claudio Yacob's first Albion goal earned his side a well-deserved point against Premier League pace-setters Arsenal at the Hawthorns.
Yacob headed the Baggies in front three minutes before half-time from a delicious cross by Morgan Amalfitano.
But Nicolas Anelka missed two great chances to double the lead and Jack Wilshere's second-half equaliser earned the Gunners the draw that took them joint top of the table.
Albion started well and a neat move forced an early corner, which was cleared by the Gunners.
And a darting run by Nicolas Anelka against his first English club caused some more problems for the visitors but he could not pick out a team-mate with his right-wing cross.
But there was a threat from Arsenal with Mikel Arteta's long-range shot deflecting wide off Olivier Giroud.
And Aaron Ramsey saw a 20-yard free-kick fly off target.
But it took a while for the match to truly come to life, with a save from Boaz Myhill late in the first half increasing the tempo.
He made a fabulous block to deny Aaron Ramsey from a Mesut Ozil corner.
And moments later the Baggies led through Yacob's first goal for the club.
He arrived in the near-post region three minutes before half-time to head home a fine cross from Morgan Amalfitano after the Frenchman's corner was returned to him.
The Baggies should have doubled their lead two minutes into the second half as Saido Berahino burst down the left and crossed to the far post, where Anelka miscontrolled and a brilliant chance went begging.
The Gunners broke and Wilshere blasted over after charging down the left.
But Anelka then missed another great chance after he tore down the left to meet a Liam Ridgewell pass.
Anelka cut inside before bending a right-footed shot just wide of the far post.
Albion were made to pay for their wastefulness on 63 minutes when Wilshere struck.
He collected a lay-off from substitute Tomas Rosicky and hit a 20-yard shot that deflected off Jonas Olsson's shin and beat the wrong-footed Boaz Myhill.
Albion head coach Steve Clarke spoke after the game: "It was a fair point, we came out and controlled the second half.
"We fancied the three points had we got that second goal. When they equalised, the game opened up and was a bit like russian roulette.
"Claudio (Yacob) is a danger in the air and we have used him in set plays and none have quite paid off but it was good to see him make the most of his chance today from a great (Morgan) Amalfitano cross.
"We pushed them back and attacked Arsenal with our four attacking players whilst Yacob and (Youssef) Mulumbu provided a screen for the back four. They showed a great work ethic today.
"Saido deserved his start after his performance at Old Trafford last weekend and he did well again today.
"We started the season slowlybut our last four games have been much better. The second half today showed that we can stand toe-to-toe with a good Premier League side so that is good for us."