Arsenal 1 Swansea 2

According to Arsene Wenger, opinions are like the weather forecast, changeable and pretty flaky. But the storm that has the Arsenal manager and his team in its grip shows no sign of abating.

After the abject 3-2 defeat at Manchester United on Sunday, which provoked bitter frustration among the club’s fan-base, this was an occasion when victory was a prerequisite. They were even up against a weakened Swansea City team.

But after a bright start, it was shocking how they lost their way. Wayne Routledge, the former Tottenham winger, cancelled out Joel Campbell's opening goal on 32 minutes and, thereafter, Arsenal looked like a team with their confidence in tatters.

It was no great surprise when Ashley Williams plundered the winning goal following a set-piece to fire Swansea's hopes of pulling clear at the other end of the table, and the soundtrack of jeers at full-time told its own story. Arsenal have now won only two of seven Premier League matches and their only consolation was Tottenham's defeat at West Ham.

The mood was captured earlier by the boos that greeted Wenger’s decision to substitute Campbell, one of their better performers and, although they hit the woodwork three times, this was no hard luck story. It was certainly no way to prepare for Saturday’s trip to Tottenham.

The pre-match drama had been in the Swansea camp, with the head coach, Francesco Guidolin, admitted to hospital having failed to shake the illness that had gripped him since last week. The squad had stayed in London since Sunday's loss at Tottenham, where the Italian suffered on the bench, his hat pulled low and his scarf high up to his eyes.

The evening was shaped by absentees, with the bigger picture being the seven changes that Swansea made from White Hart Lane. It seemed like a selection that was designed to keep key players fresh for the challenges with more direct rivals which lie ahead. They entertain Norwich on Saturday and after that they play Bournemouth away and Aston Villa at home.

It was good news for Arsenal, and they surged into an early lead. Campbell had looked in the mood from the first whistle and his goal was a beauty. Alexis Sanchez lofted a ball into the area for him to chase, which he did, and just when it appeared that it might be beyond him, he slid for it, snaked out his left leg and hooked an expert finish into the far corner.

Campbell was one of three changes that Wenger made to the line-up that played at Old Trafford, with Olivier Giroud being another. He came in for the scapegoat of the moment, Theo Walcott, and he endured nervous moments. There was one horribly misplaced back-heel and a weak finish from Hector Bellerin's smart cut-back at the start. He had also snatched at the very first chance of the match. The home crowd chuntered.

Giroud would also smash a volley against the crossbar from 10 yards on 41 minutes, following Per Mertesacker’s cushioned header back to him. The connection was clean and there was an element of bad luck, but the Frenchman ought to have done better.

Wenger's other change saw Mertesacker replace Laurent Koscielny, who had a calf strain. The concern was that Koscielny might struggle to make the derby on Saturday.

For the opening 25 minutes, Arsenal were in charge. Sanchez hit a post in the 11th minute, after mis-kicking a volley in the first phase of the move, while Bellerin warmed Lukasz Fabianski's palms from distance. But after Leroy Fer had fizzed a shot over the crossbar, the visitors stunned the Emirates.

All it took was one simple straight pass from Jack Cork which set Wayne Routledge clean through after Jordi Amat had contested a Petr Cech clearance with Mesut Özil. Amat was all over Ozil, and the ball broke off the Arsenal playmaker.

Wenger argued that Bafetimbi Gomis should have been flagged for offside on Cork's through-ball but he was not interfering with the play. Routledge's finish was ice-cool. Alan Curtis, the Swansea coach, introduced Gylfi Sigurdsson at half-time, as he sensed a result and it became yet another test of nerve for Arsenal. The frustration simmered in the stands; the howls of anguish undercutting the attempts at encouragement.

Arsenal grew more and more ragged, their build-up work lacking structure and Swansea, by contrast, became convinced that there was something in this for them. Sanchez had a shot deflected wide and he also failed to connect with an Özil free-kick but as the second-half minutes ticked down, so the crowd grew more restless and the Arsenal players more nervous.

There was fury when Fer went down on 62 minutes and Arsenal chose to stop the play – they are too nice to play on – and there was open mutiny when Wenger hooked Campbell moments later.

Sigurdsson made the difference. He almost scored following a burst on to Andre Ayew’s pass, going around Cech but failing to finish but, after Sanchez had seen a free-kick deflect and come back off the crossbar, Sigurdsson helped Swansea into the lead. From his whipped free-kick from the right, the Arsenal defence froze, Cech flapped and Williams bundled home.

For Wenger and his players there would be no escape. Cech came up for a last-gasp corner, which came to nothing and as he ran back, it looked as though he pulled a muscle.

It seemed like a fitting finale.

(Guardian service)