Arsenal beat West Brom at the Emirates on Monday evening with two goals from record £53 million signing Alexander Lacazette.

Tony Pulis and his men could feel aggrieved by referee Bobby Madley turning down a cast-iron penalty for the Baggies in the first half when the scores were level as Arsene Wenger’s men made them pay.

Danny Welbeck was missing after his groin strain picked up during the 0-0 at Stamford Bridge last time out, while Alex Iwobi was dropped. Mohamed Elneny made his first start since the opening day of the season, while Wenger finally named Alexis Sanchez in the starting XI for the first time this season at home.

West Brom made three changes as Tony Pulis brought in Allan Nyom, Jake Livermore and Hal Robson-Kanu step up to replace the benched James Morrison, Chris Brunt and Matt Phillips.

Arsenal went 1-0 up on 20 minutes after Lacazette showed the value of following up. Alexis Sanchez took a deftly-flighted free-kick from a central position on the edge of the box that flew over the wall and Ben Foster onto the bar before the former Lyon player gave an example of his predatory instincts by heading home from close range.

Gareth Barry proved that appearances matter by starting his record-breaking 633rd Premier League appearance – and deservedly so given his consistency and professionalism.

But it was the £53m Frenchman who was also breaking a record – becoming the first Arsenal player to score in his first three home games for the club since Brian Marwood in that glorious autumn of 1988.

Marwood’s record, of course was not a real one as everyone knows football wasn’t invented until 1993, but even so it was nice to see George Graham’s influential wideman - for that one stunning season - get a mention from the social media statisticians.

Albion could have been ahead by that point as they had a valid penalty appeal turned down by referee Bobby Madley after Jay Rodgriguez had his legs swiped from under him in the box following a poorly-timed challenge from Shkodran Mustafi.

Pulis was incandescent at the poor decision choosing to harangue the fourth official Stuart Attwell. He was right to be annoyed, but perhaps he should have saved some of his ire for the wayward finishing of his forwards immediately afterwards.

Rodriguez got to his feet immediately to fire the ball across Petr Cech that the experienced keeper tipped onto the post. Jake Livermore, perhaps momentarily surprised by what was unfolding in front of him, then fired wide when he should have scored.

Arsenal might have won six successive home matches against West Brom in the Premier League, conceding just the one goal - but memories among the more wary of us were still fresh from another of Wenger’s spring humiliations – the 3-1 thumping at the Hawthorns.

Who can forget that dull Midlands day when the only reason to look up into gunmetal grey skies was to work out whether the tedious buzzing from low-flying aircraft was from pro or anti Wenger factions.

It was even worse on the pitch as two thumping headed goals from Craig Dawson highlighted a desperately poor defensive display. Wenger admitted at the start of this season that his indecision in whether to stay on for another two years affected his team.

Anyone who was at West Brom that dreadful day could have told him that. You know things are bad when even Tony Pulis in his post-match press conference took pity on the Frenchman.

Six months on, what exactly has changed?

Yes, Arsenal played well in attack.

But they were also disorganised, ponderous and porous against the enterprising visitors who grew in confidence when they realised there wasn’t so much a lack of zonal marking as any semblance of marking full stop.

Nacho Monreal was hailed for clearing off the line before half time, but surely the question should have been why two Baggies forwards were left unmarked in the box waiting for a cross?

Cech then got his foot to Rodriguez’s close-range shot as the ball squirmed just wide.

And as referee Madley blew for the interval and Wenger’s team fortuitously leading 1-0 the feeling was West Brom were unlucky not to be level – or even in front.

Six months on from that Hawthorns debacle what exactly had changed?

Arsenal made it 2-0 on 65 minutes after Ramsey drove into the box near the byline. Allan Nyom barged into him sending him flying. Madley rightly decided it was a penalty and Lacazette stepped up to send the ball low into Foster’s left hand side.

You had to feel for West Brom. Even their official Twitter showed evidence of the bone-dry West Midlands sense of humour by posting: ‘Referee Madley gives a penalty this time and Lacazette scores.’

As the clock ticked down Lacazette was replaced by Olivier Giroud as both men received a thunderous round of applause.

It was interesting to hear volume much lower for Sanchez as Mesut Ozil came on. It could just be that Lacazette had earned an ovation for both his goals. And that fans were pleased to see Giroud on the pitch as he hunts for his 100th Arsenal goal.

But you can’t help feeling that much as Arsenal fans love Sanchez, his intransigence over the summer resulted in the bond between him and Gunners fans being ruptured.

As it will when he eventually leaves after his runs his contract down.

But for now Arsenal picked up a welcome three points in their hunt for – well, given the schizophrenic nature of this team, no-one can quite work out exactly what they are hunting for at the moment.

Because a defensive display against the might of Manchester City in November will lead to another humiliation on the scale of Liverpool away.