Mikel Arteta struck twice from the penalty spot - the first after a dive by fellow Spaniard Santi Cazorla - as Arsenal returned to winning ways with a Premier League victory over West Brom at Emirates Stadium.
The Gunners had started brightly but took the lead through controversial fashion, after Cazorla flung himself to the floor following a challenge by Steven Reid when replays showed there was no contact.
The Baggies, who lost twice last week to halt their fine start to the season, never really recovered from the sense of injustice and there was no way back once Arteta converted from the penalty spot again on 64 minutes after Chris Brunt had tripped Alex Oxlade-Chamberlain.
It was a lively start by the home side, who had not won in four games, but recalled most of their first-team regulars missing from the midweek Champions League defeat at Olympiacos, although forward Theo Walcott was sidelined by a calf injury.
A high pass into the West Brom penalty area was palmed away by Boaz Myhill, but Gervinho missed his kick and could only hack the ball wide from six yards.
West Brom were forced into an early change when defender Liam Ridgewell hobbled off, replaced by Goran Popov.
On 17 minutes, Oxlade-Chamberlain darted to the goalline on the right and looped the ball back across goal. Cazorla arrived at pace, but could not keep his left-foot volley down and fired the ball high into the Clock End.
West Brom were dangerous on the counter and almost snatched the lead when captain Chris Brunt curled a 20-yard effort just wide of the top right corner.
Arsenal were awarded a penalty on 24 minutes. Cazorla cut into the left side of the area, and as he turned back inside Steven Reid, went to ground as the defender stuck out his leg.
Referee Mike Jones immediately pointed to the spot, although television replays showed there looked little contact, if any at all. Arteta stepped up to drill the ball past Myhill.
There was more than a sense of injustice from the visitors, who soon went in search of swift recompense.
However, Arsenal soaked up the pressure and then resumed their counter attacks.
Gervinho ghosted down the left and pulled the ball back across the face of goal, but Jack Wilshere's sliding touch stabbed it just wide.
West Brom felt they had a penalty shout when Per Mertesacker handled a high ball in the Arsenal box, but the assistant on the far side flagged for a foul on the big German defender by Jonas Olsson.
At the other end, Myhill pushed a low shot from Gervinho around the post before Oxlade-Chamberlain sent an acrobatic scissors kick over the crossbar.
West Brom started the second half with some purpose, yet not really stretching the Arsenal defence.
The Gunners went forwards quickly on the counter, with Oxlade-Chamberlain floating a ball across the face of goal before Olivier Giroud and Olsson squared up on the edge of the penalty area, with the referee soon restoring calm after showing both players a yellow card.
Gervinho was off target again when he glanced a free header wide on the penalty spot.
The Ivory Coast forward was enduring one of those afternoons when moments later he failed to connect with Giroud's knockdown into the six-yard box.
On 64 minutes, Arsenal were awarded another penalty.
This time there was no controversy as Brunt chopped down Oxlade-Chamberlain after the England midfielder had charged down the right.
Arteta took it again and with the same outcome as the Spaniard blasted the spot-kick down the middle.
With a two-goal cushion, Arsenal had some breathing space and started to produce the slick, passing football which had been so lacking in recent performances.
With 13 minutes left, Wenger sent on defensive midfielder Francis Coquelin for Oxlade-Chamberlain.
Arteta tried for a hat-trick when he whipped a 22-yard free-kick around the wall, but also just past the left-hand post.
West Brom substitute Markus Rosenberg tested Arsenal keeper Wojciech Szczesny with a low shot from 20 yards.
German international Lukas Podolski came off the bench to somehow lift the ball over from six yards as Arsenal closed out what was in the end a comfortable victory to edge back up towards the top four.