After all the fun they have had racking up victory after victory, Arsenal will no doubt be aggrieved the winning run is over. But they are back on top of the Premier League and at least Arsène Wenger can be encouraged by their response when it seemed as though they could easily go the same way as Manchester United had the previous weekend.
They certainly had their work cut out after a prosaic first half probably best epitomised by Jack Wilshere's dislocated, tetchy body language and the overwhelming sense that West Brom's first win at Old Trafford since 1978 had helped to re-energise Steve Clarke's side.
Claudio Yacob had scored his first goal for the club, powering in a header three minutes before the interval, and at that stage there was not a great deal of evidence to show this was an Arsenal team going for 11 wins on the bounce. Wilshere's shoulders had started to sag. Frustrated possibly at being played out of position, he was missing the usual sureness of touch and, in the worst moments, wearing a look of almost self-revulsion on his face.
Olivier Giroud was a difficult opponent all afternoon, particularly with his back to goal, but the midfielders running on to his clever little layoffs and touches were struggling collectively to exert any sense of clear control. Arsenal certainly took their time to find their usual fluency.
Even Mesut Özil, showing his refinement in the second half, looked a little peripheral during those moments when West Brom reminded us, in pockets of quick, attacking football, why they had just beaten the champions. Arsenal should be grateful, ultimately, that Nicolas Anelka is 34 now. The younger, more clinical Anelka the jet-heeled teenager once of Arsenal, for example would surely have taken one of the two opportunities that presented themselves to make it 2-0 at the start of the second half.
On that basis alone, Arsenal got a little lucky, even discounting the fact that Wilshere's equaliser took a hefty deflection off Jonas Olsson.
Anelka missed two chances he would once have scored as habit and Arsenal, slowly but surely, shook their heads clear and started to play with some of the attacking zest and confidence that has been their forte over the last six weeks. Wilshere, in particular, answered a few questions about his competitive courage, becoming increasingly influential as the game went on. He had started on the left wing, then switched with Aaron Ramsey to go to the right.
He had a go at swapping positions with Özil, went back to the left and finished on the right. Wilshere no doubt yearns for an orthodox central role but at least he kept going, after a difficult start, and made a telling contribution with his goal.
Arsenal had enough of the ball in the closing exchanges to believe they could have won but Clarke could also say the same of West Brom from earlier in the match without it sounding unreasonable. Arsenal accumulated the greater number of chances but Anelka's were the more inviting and the pacy, direct running of Saido Berahino, Stéphane Sessègnon and Morgan Amalfitano created plenty of problems. After a slow start to the season, Clarke's team have developed a fluent, counter-attacking system with plenty of pace. It is just a pity for them that Anelka is not the player of old.
Arsenal had shaded the opening 30 minutes but West Brom were certainly the more dangerous team towards the end of the first half and that burst of pressure paid off when Youssouf Mulumbu, playing with some distinction, picked out Amalfitano on the wing to set up Yacob for the opening goal. The cross was delivered with pace and accuracy, Carl Jenkinson was not close enough to Yacob and the Argentinian's header was powered downwards, bouncing off the turf to beat Wojciech Szczesny.
Wilshere had looked so off the pace, picking up a booking for a challenge that seemed shrouded in frustration, it was almost a surprise Wenger kept him on for the second half. As it was, the substitutions started with Ramsey, who was not running freely, going off for Tomas Rosicky. Yet Wenger ultimately had it spot on. Rosicky was prominently involved for the remainder of the match, whereas Ramsey, having taken a knock, was not up to his recent standards. Whatever was said to Wilshere at half-time clearly had galvanising effects, too. The midfielder became a far more accomplished opponent when he stopped feeling sorry for himself and started reminding everyone of his gifts.
After 62 minutes, Giroud came in from the right and squared the ball for Rosicky. Wilshere was on to the layoff in a flash. Wenger said afterwards he never expected Wilshere to become a prolific goalscorer but a midfielder with his talent can improve this part of his game just consider Ramsey's scoring this season and it was a cracker of a shot, even if there was a good deal of fortune involved in the way it skimmed off Olsson to elude Boaz Myhill.
The lesson for West Brom is that, facing a team this accomplished, they cannot be so generous with their own finishing. For Anelka's first chance, Berahino sprinted clear on the left then turned the ball across the penalty area only for Anelka to get it caught in his feet. Soon afterwards Anelka burst through the right side of Arsenal's defence, cutting in diagonally before trying to curl his shot beyond Szczesny.
It was a harder chance than the first but still the kind of opportunity he used to take as a matter of routine. His shot drifted wide and Arsenal have been playing with so much confidence there was always the likelihood it would be a key moment.
Man of the match: Claudio Yacob (West Bromwich Albion)