West Brom made a lively start to the game as they looked to put their recent poor form behind them, and came close to taking the lead after a bright start. Claudio Yacob got into a fine position from a corner, but his glancing header was cleared off the line by Tomas Rosicky, before the Argentine attempted to hook the ball over his shoulder to catch Lukasz Fabianski off his line, but his effort dropped wide.
Against the run of play, however, it was the Gunners who opened the scoring, as Gervinho showed some fine trickery down the left wing to leave Billy Jones with twisted blood, cutting inside and arrowing a shot into the far corner which Tomas Rosicky interrupted with a fierce header that gave Ben Foster no chance at all.
West Brom almost equalised soon afterwards however, as Chris Brunt attempted to catch Fabianski out with a free-kick at the near post, but with the Baggies lurking for the rebound, the Pole managed to hold onto the ball. Regardless, Arsenal had gotten themselves on top, and almost doubled their lead with some wonderful flowing football from Santi Cazorla and Olivier Giroud - the Spaniard threaded a brilliant pass through for the striker, whose backheel found the onrushing Aaron Ramsey, but his toe-poke was wide of the goal.
Not long after half-time, Arsenal appeared to get a killer second goal, again through Tomas Rosicky. The Czech midfielder was released to test Foster with one effort, but the rebound came straight back out to the Czech and he made no mistake the second time, firing home to put the game seemingly out of West Brom's grasp.
West Brom felt they should have had a penalty when James Morrison tried some nifty footwork to dance past the Arsenal defence, and Per Mertesacker appeared to handball to deny the opportunity. Replays showed, however, that the German simply fell over and landed on the ball with his arm glued to his side, so the correct decision was made.
That didn't matter for long, however - West Brom soon had their penalty, and a red card for Mertesacker to boot as one incident turned the game on it's head. Shane Long was set free in the area with the German defender out of position, and his terrible attempt at a recovering tackle got none of the ball and all of the man, which saw the referee point to the spot and duly dismiss the centre-back.
James Morrison's penalty was scruffy, straight down the middle and off Fabianski's legs, but it found the net regardless and heralded a siege on the Arsenal goal for the remainder of the game. The Gunners simply couldn't clear their lines at all as West Brom bombarded them for twenty minutes in search of a goal.
First Romelu Lukaku missed a fine chance as the ball rolled to him in the left channel a few yards from goal, but his attempted curled finish to the far corner drifted just wide of the post. Shortly afterwards, Shane Long also found space to escape his marker down the left channel, but his fierce effort flew over the bar.
West Bro's profligacy appeared to have saved Arsenal, and despite five minutes of added time being awarded, the hosts could not force another chance, and Arsenal held on for a fortunate victory.