Bidding to follow up last weekend’s shock victory at Manchester United, West Brom took a 42nd-minute lead at The Hawthorns when Claudio Yacob converted Morgan Amalfitano’s right-wing cross with a near-post header.
Former Arsenal striker Nicolas Anelka spurned two glorious opportunities to double the hosts’ lead, fluffing his lines from Saido Berahino’s low cross and then curling wide with only Wojciech Szczesny to beat.
He was made to pay for his profligacy in the 63rd minute when Jack Wilshere met Tomas Rosicky’s lay-off with a crisp drive that took a deflection off Jonas Olsson and flashed past goalkeeper Boaz Myhill.
Myhill prevented Olivier Giroud from claiming a late winner, but the draw was enough to take Arsene Wenger’s side above Liverpool on goals scored, while Steve Clarke’s West Brom remain 12th.
“It was breathless,” said Arsenal manager Wenger.
“West Brom showed why they won at Manchester United last week and we had a hell of a task to come back, but we showed character and we had chances to go on and win it.
“Our position is good because when you look at how we started (losing 3-1 at home to Aston Villa) and now we’ve come out of two away games well, so it’s a good position to start again after the (international) break.”
Tottenham Hotspur could have moved level on points with the leaders, but they were dealt a stunning 3-0 home defeat by London rivals West Ham United.
After a quiet first half, Spurs appeared to be hitting their stride in the second period when Winston Reid put West Ham ahead in the 66th minute, smashing home after Kevin Nolan had inadvertently blocked his header.
Ricardo Vaz Te added a second goal six minutes later, the ball ricocheting off his thigh and into the net after Hugo Lloris blocked his initial attempt, before Ravel Morrison completed the scoring with a fine solo goal.
Asked if the result was a wake-up call, Spurs manager Andre Villas-Boas replied: “It is. This fixture was a bit dangerous.
“If we won, everything would be spectacular, but if you draw or lose, you drop into a position you don’t want to be. Either way, we have done well so far.”
The result leaves Spurs in sixth place, three points below Arsenal and Liverpool, while West Ham leap out of the bottom three to 13th.
Earlier, Eden Hazard and close-season signing Willian came off the bench to score decisive goals as Chelsea won 3-1 at Norwich City.
The visitors took a fourth-minute lead when Oscar drilled home from Demba Ba’s lay-off, but Norwich gradually took the upper hand and equalised in the 68th minute.
Martin Olsson’s deep left-wing cross was headed back across goal by Ricky van Wolfswinkel and Anthony Pilkington ghosted in behind David Luiz to glance a deft header past Petr Cech.
Chelsea manager Jose Mourinho reacted by sending on Hazard and Willian, and it proved a masterstroke.
Hazard completed an 85th-minute counter-attack with a low shot that squirmed beneath John Ruddy to put Chelsea ahead before Willian curled home a glorious left-foot shot a minute later to claim his first goal for the club.
“When I make a change, the change is always fantastic and the players make it fantastic or make it rubbish — it’s up to them,” said Mourinho.
“I’m happy for Willian because he is starting with us, he is not 100 percent. He was injured in the week and the kid made himself available to try to help, and when he came on he gave us a push.”
The two late goals elevated Chelsea to third place, two points beneath Arsenal and Liverpool, while results later in the day saw Norwich slip into the relegation zone.
Southampton continued their fine start to the season by winning 2-0 at home to Swansea City, which sent Mauricio Pochettino’s side to the dizzying heights of fourth place.
Saints captain Adam Lallana broke the deadlock in the 19th minute when he polished off a fine pass from Steven Davis.
Goalkeeper Artur Boruc thwarted Swansea on several occasions as the visitors pushed for an equaliser, before Jay Rodriguez made the game safe with seven minutes remaining.