By Neil Ashton
It all came down to a lucky strike for Jack Wilshere. His equaliser at the Hawthorns deflected off the shin of Jonas Olsson and preserved Arsenal's slender lead over Liverpool.
Wilshere's timing was perfect, the ideal response to being caught having a crafty puff on a cigarette outside a nightclub after Tuesday's Champions League win over Napoli.
'He's an honest boy and he knows when he has made a mistake,' said Arsenal manager Arsene Wenger. 'He learns quickly and he knows that the rules of modern society are a lot different and you cannot get away with it. There is not much to say to him. We got away with more in my day, but I couldn't tell you whether he has packed them in.'
VIDEO Scroll down to watch Arsene Wenger and Steve Clarke reactions
The equaliser: Jack Wilshere celebrates the goal that rescued Arsenal from defeat at West Brom
WEST BROM: (4-4-1-1) Myhill 7, Jones 7, McAuley 7, Olsson 7, Ridgewell 6; Amalfitano 7, (Brunt 89) Mulumbu 9, Yacob 8, Berahino 8; Sessegnon 8; (Morrison 78, 6) Anelka 5. (Long 69, 6)
Subs: Daniels, Popov, Rosenberg, Lugano.
Goals: Yacob 42
ARSENAL: (4-4-1-1) Szczesny 7, Jenkinson 6, Mertesacker 7, Koscielny 6, Gibbs 7; Ramsey 5, (Rosicky 59, 6) Arteta 7, Flamini 7, Wilshere 7; Ozil 6; Giroud 7. (Bendtner 85)
Subs: Fabianski, Vermaelen, Monreal, Miyaichi, Gnabry.
Bookings: Flamini, Wilshere
Goals: Wilshere 63
Ref: Lee Mason
*Player ratings by Neil Moxley at The Hawthorns
He likes his new song 'Jack Wilshere, he smokes when he wants' tweeting as much after the travelling support celebrated his first league goal since November 2010. Yesterday's equaliser was far more important than a late goal against Aston Villa in a 4-2 victory nearly three years ago.
Wilshere meets up with the England squad later today and his team are guaranteed to be top of the table for the next two weeks.
He showed his class in the build-up to the equaliser, anticipating Tomas Rosicky's lay-off on the edge of the area. He could easily have had a penalty earlier when Billy Jones brought him down, but referee Lee Mason ignored Arsenal's appeals.
His goal arrived at a time when West Brom threatened to increase their lead. A week after they beat champions Manchester United 2-1 at Old Trafford, Steve Clarke's team were still buzzing.
They deserved their lead, given to them when Claudio Yacob, one of the best screening midfielders in the Premier League, scored his first goal for the club. It was worth the wait as he directed a header beyond Arsenal goalkeeper Wojciech Szczesny in the 40th minute.
The Argentinian's celebrations were brilliant, pumping his fists and raising his knees as he set off towards West Brom's supporters behind the goal.
Midfield battle: Arsenal's in-form Aaron Ramsey vies for possession with Liam Ridgewell
Classy: Germany international Mesut Ozil again impressed for the Gunners
The opening goal: West Brom's Claudio Yacob headed his side in front in the 42nd minute
Here's how Claudio Yacob scored West Brom's goal now click here for your brilliant bumper stats zone from The Hawthorns
Time to celebrate: Yacob is congratulated on his goal by team-mates Nicolas Anelka and Stephane Sessegnon
Dejection: But Arsenal soon battled back to get on level terms
Aerial battle: Arsenal's Laurent Koscielny beats West Brom's Billy Jones to the ball
That's when Arsenal's unbeaten away run, stretching back to their 2-1 defeat at White Hart Lane in March, looked in most danger. Clarke's side were superb, pushing the ball across the pitch with confidence as they went in search of a second.
Until he was substituted, Stephane Sessegnon was the best player on the pitch, standing out in bright orange boots with his relentless runs. He set up Nicolas Anelka at the start of the second half but the West Brom forward mistimed his run and the ball stuck under his feet inside the six-yard box.
Then Anelka burst clear of Carl Jenkinson, curling a right-foot effort wide of the far post.
It was stirring stuff in front of 25,000 supporters and Clarke said: 'A point was no more than we deserved because we played very well. We had great opportunities to make it 2-0 and that would've been enough.
World-class: Jack Wilshere struck a quality equaliser as the second-half progressed
'Nicolas is an experienced striker and was in the right position. The first chance arrived behind him, and with the second he did almost everything right. Strikers need goals, but if he keeps getting into the right position he will score.
'This was another good game for us and to get four points out of Arsenal and Manchester United is good.'
For the first time this season in the Premier League, Arsenal failed to score first, but their response was excellent. After Wilshere's goal, Olivier Giroud was denied a winner when West Brom keeper Boaz Myhill saved brilliantly at his feet.
Arsenal soaked up considerable pressure at the start of the second half and Wenger conceded it had been a fair result. 'It's a comfort, a mental comfort, to be at the top in the international window,' he said. 'It was important not to lose after we went a goal down.'
After guaranteeing top spot, it's left them gasping for more.
Crucial: Olivier Giroud celebrates Wilshere's impressive equaliser
Stretching: Arsenal left-back Kieran Gibbs attempts to stop the ball going out of play
Fans' favourite: Wilshere was among those to throw his shirt into the crowd after the final whistle
Jack Wilshere was pictured with a cigarette in his mouth during the week and has been reminded about his responsibilities by Arsenal manager Arsene Wenger despite denying being a smoker.
Wenger opted against leaving him out of the side to face West Brom and here Sportsmail assesses his impact in the match.
Wilshere's lungs did not let him down against the Baggies as his influence increased the longer the game progressed. A slow start, but he had more running in him than most as the game reached its final quarter.
Not Wilshere's finest attribute on the day. He spent plenty of time complaining to officials for every perceived slight. Hit the deck on half a dozen occasions or more, thrusting his arms out to his side each time in order to draw attention to his supposed ill treatment. Most tackles seemed fair enough and he may need to toughen up to avoid a repeat.
With Mesut Ozil dominating the central playmaker's spot nowadays, Wilshere was stationed wide left and then wide right. Shielding his full-back seemed an optional extra at times, though, and he was also compromised badly early in the second half when Nicolas Anelka drifted into space between him and Carl Jenkinson. Was also skinned on two occasions by Morgan Amalfitano and Youssouf Mulumbu.
Going forward is clearly the England midfielder's preference and it showed. A quiet first half did not stop him shooting wide after a neat one-two and he spent plenty of time in the final third as the second half went on. Got a good connection for his deflected goal and produced a fine lobbed pass which Olivier Giroud should have finished.