Tomas Rosicky grabbed a brace as 10-man Arsenal squeezed out a crucial victory at West Brom on Saturday.
The Czech international headed home Gervinho’s cross midway through the first half and cracked home a second just after the restart to give Arsène Wenger’s side complete control.
However the game changed in the 70th minute when Per Mertesacker brought down Shane Long and James Morrison scored from the spot to reduce Arsenal's lead. The German was sent off.
West Brom threw everything at the visitors in the remaining time but Arsenal rolled up their sleeves up and battled.
They held on for a vital three points that puts them in the top four, albeit temporarily.
Arsenal have now secured seven wins and a draw in their last nine Premier League games - and this was as crucial and tight as any of them.
It was a victory of immense value.
Before kick-off, Wenger retained the side that has swept aside Reading last weekend. The only significant change was on the bench where Vito Mannone replaced Wojciech Szczesny.
The last time Arsenal had played at The Hawthorns they had secured third place in the Premier League table at the expense of Tottenham. That was a nervy conclusion to the 2011/12 campaign last May.
West Brom had spent the first half of this season in the top six and, although they had fallen away slightly, had never been out of the top nine.
They were a significant test but Arsenal started the afternoon brightly by pressing back their hosts.
But the first real chance would fall to the home side.
In the 12th minute, Claudio Yacob’s header was nodded off the line by Rosicky at the far post. West Brom recycled the ball and when Lukasz Fabianski failed to claim the ball Argentine flicked a shot on to the roof of the net.
It brought West Brom back into the game briefly but, in the 20th minute, Arsenal took the lead.
Gervinho twisted and, quite literally, turned Gareth McAuley on the left-hand side of the area. His cross was converted at the near post by Rosicky’s darting header.
The goal was his first in the Premier League this term and just desserts for the Czech midfielder’s energy and artistry in the first half.
In the 24th minute Rosicky clipped Billy Jones and Chris Brunt sent a low free-kick scuttling towards the near-post. Fabianski made a comfortable save.
But every time West Brom pressed, Arsenal would respond. It allowed the visitors to keep their noses in front.
Gervinho fooled Liam Ridgewell to find himself some room on the right but his angled shot was booted away by Foster. The rebound fell to Ramsey but the keeper held on to his drive.
W.B.A. 1 - 2 Arsenal
Watch the entire second half from the Hawthorns
Watch the key moments from the Hawthorns
Catch up with all the key moments from the game
Watch the entire first half from the Hawthorns
And three minutes before half-time Arsenal should have doubled their lead. A deft flick from Olivier Giroud allowed Aaron Ramsey to emerge unmarked in a crowded area. But, from just eight yards out, he prodded wide with the goal gaping.
Arsenal went into half-time with a crucial lead on the back of a decent display. But there was work to do.
After the restart, Gervinho set up Sagna on the overlap six yards out. Foster flew out and managed deflect his shot behind.
However Arsenal would not wait long for a goal.
Rosicky drove forward and although Foster batted down his first shot the midfielder thumped the rebound into the net before celebrating enthusiastically with the Arsenal fans behind the goal.
It was the comfort that visitors needed but West Brom still had their ambition.
Morrison claimed a penalty when Mertesacker fell on the ball in the area. Referee Howard Webb rightly waved away all appeals.
Then the German put Koscielny in trouble and his fellow centre back clipped Long. Romelu Lukaku fired the free-kick straight at Fabianski.
After that, Brunt escaped and drew a fine save from the keeper at the near post.
West Brom were starting to press and soon they broke through.
Mertesacker swept the legs away from Long as the West Brom striker chested down a aerial ball just inside the area.
It was a clear foul and therefore Mertesacker had to see red. Morrison just squeezed his penalty past Fabianski.
Before the restart, Thomas Vermaelen replaced Gervinho as Arsenal re-jigged.
All of a sudden the game was very, very different.
West Brom peppered the visitors area with crosses in the following 10 minutes and they came closest when Gareth McAuley slid a header wide at the far post.
The home side were laying siege to the Arsenal goal and the visitors could not sustain anything in attack themselves.
As the seconds ticked away, Lukaku curled an effort inches past the far post from eight yards when he really should have scored.
Three minutes from time, Long grazed the crossbar from close range.
It only got more tense in injury time but Arsenal held on.
At the full-time there was only one emotion – relief.
Wenger's men had won the 'first game' - the one before the sending off - and done just enough in the second after the dismissal.
Referee: Howard Webb
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