Two goals from Alexandre Lacazette, one in either half, gave us a hard-fought win at Emirates Stadium.
His brace took the striker's tally to four goals from three Emirates Stadium appearances this season, and all three games have ended in victory.
The first was a poacher's effort after Alexis struck the bar from a free-kick, the second came from the penalty spot after Aaron Ramsey was bundled over.
It was enough to give us all three points, but we survived two huge let offs along the way. Petr Cech made a excellent fingertip save and Nacho Monreal cleared off the line – both from Jay Rodriguez – during an eventful first half.
It was Alexis, back in the starting lineup, who had our first shot at goal – a direct free-kick that fizzed just wide.
We survived our first let off inside the opening 10 minutes. Shkodran Mustafi mistimed his tackle on Rodriguez inside the area, but rather than give the penalty, the referee allowed play on as Rodriguez picked himself up and fired goalwards. Cech dived to his left and made a fantastic low save to flick the ball onto the post, and Jake Livermore scuffed the rebound wide.
The Emirates faithful breathed a sigh of relief.
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Aaron Ramsey headed over from a Hector Bellerin cross as we tried to work our way back into the game.
It was a fairly even opening 20 minutes, until we took the lead. Mohamed Elneny was fouled just outside the area, Alexis curled his free-kick against the bar and Lacazette pounced from close range.
At the other end former Gunner Kieran Gibbs flashed a speculative effort over, but we were on the front foot now.
Alexis struck another free-kick wide as Arsenal put the visiting defence under increased pressure.
As the half drew to a close, we were indebted to Monreal, who made a spectacular, acrobatic clearance to prevent Rodriguez heading Albion level.
The visitors certainly ended the half on top, and our defence had to stand firm as West Brom won a succession of corners.
The half-time break allowed us to settle, and we began the second period full of intent.
Lacazette saw an effort charged down when Mohamed Elneny laid the ball off to him in the area before we doubled the lead from the penalty spot.
Ramsey did superbly well to beat Allan Nyom by the touchline inside the area, and the Cameroonian defender bundled him over.
Lacazette made no mistake from 12 yards.
We were in control now. Lacazette nearly had his hat-trick but he smashed over after taking the ball round Ben Foster, and Hector Bellerin saw his long-range goalbound effort well saved by the keeper.
The manager brought on Mesut Ozil and Olivier Giroud for the final few minutes.
The latter set up Ramsey in the box late on, and the Welshman forced another good save from Foster.
It's five unbeaten now, and some momentum is starting to build.
ALEXIS AND LACAZETTE WATCH
This was the first time the two forwards had been on the pitch at the same time this season, and they combined well to take us to victory.
5 Alexis is fouled on the edge of the area, takes the free-kick himself and whips the shot just wide.
20 Alexis strikes another free-kick, which hits the bar and Lacazette is in the right place to head home the opener.
26 Alexis dummies for Lacazette on the edge of the area, but the ball doesn't quite run for the Frenchman.
32 Alexis threads a superb defence-splitting pass through to Ramsey in the area, but Ben Foster saves.
36 Another Alexis free-kick, this time from slightly further out, is sent just wide.
51 Lacazette's shot from inside the area is deflected over the bar after good work from Alexis and Sead Kolasinac on the left.
61 Alexis beat two players with a neat dragback, and crossed towards Lacazette, but Foster intercepted.
67 Lacazette strokes his penalty into the bottom right corner after Aaron Ramsey was fouled by Allan Nyom.
70 Lacazette smashes the ball over from a narrow angle after Alexis found him with a deep, searching pass.
83 Both players are withdrawn to a well-deserved Emirates ovation.
WHAT IT MEANS
We kept our 100 per cent home record in tact to rise from 12th to seventh in the Premier League, six points behind the early leaders.
Our first away match in the Europa League is coming up on Thursday, and the boss is expected to make wholesale changes for the 1,200 mile trip to Minsk in Belarus to take on BATE Borisov. Then it's another home game in the Premier League, against Brighton, on Sunday.
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