Premier League: Arsenal 1 Chelsea 2

Chelsea extended their unbeaten start to the season and their lead at the top of the Premier League as two set-piece goals won the London derby at the Emirates.

Juan Mata’s free-kicks were to prove the scourge of the Gunners, who lost their unbeaten tag for the season, as the former Valencia man set up Fernando Torres for the opening goal and then saw his second-half effort deflected into his own net by Laurent Koscielny.

In between, Arsenal had drawn level just before the break with a fine goal from Gervinho, and in truth there was very little between these two sides. But, just when the plaudits had been pouring in for Arsenal’s new-found defensive resolve, it deserted them in damning fashion for both goals.

While Wenger’s main selection dilemma was supposed to be in attack, he ultimately pulled something of a surprise in defence by preferring Koscielny to Per Mertesacker. It was a decision he may look back upon with some regret for the remainder of the weekend.

The big German had overcome a difficult first season and looked comfortable in the opening five games, but Wenger opted to keep faith with Koscielny, who had stepped in for Thomas Vermaelen at Manchester City the previous weekend. The Frenchman had scored a fine equaliser that day, but here he was badly at fault for both Chelsea goals.

Up front for Arsenal Gervinho started in the lone striking role, as he had done at Manchester City, with Lukas Podolski and Aaron Ramsey providing support from the flanks.

That was the combination that had taken the game so impressively to the champions six days earlier, but Chelsea’s rearguard have been in rather more miserly form and immediately looked a harder nut to crack.

As expected John Terry started for the visitors despite his tumultuous week off the pitch, and Frank Lampard was deemed only fit enough for the bench so Ramires came in to defensive midfield alongside Jon Obi Mikel, while the trio of Mata, Eden Hazard and Oscar operated behind Torres.

Cazorla and Kieran Gibbs did put one decent move together down the left flank, but the Gunners’ early rhythm was interrupted by the worrying injury to Abou Diaby, who limped off gingerly to be replaced by Alex Oxlade-Chamberlain.

Arsenal were still adapting to that change when Chelsea took a surprise lead. Mata floated in a free-kick from the right and the home back four were seemingly flatfooted, with Koscielny outmanoeuvred by Torres at the far post, the Spaniard snaking a leg free to volley impressively past Vito Mannone.

The goal gave Chelsea added impetus and momentarily Arsenal were rocking, especially Koscielny who made a hash of a routine high ball and allowed Torres another free run at goal.

The �50m man attempted to go round Mannone, but as he did so Koscielny got back to intercept. Whether or not the French defender made any contact with the ball was debatable, but the referee Martin Atkinson waved away Torres’s penalty claims.

With Oscar and Hazard proving elusive, the European Cup holders started to look genuinely dangerous, but just as they threatened a second, Arsenal got back on level terms.

The substitute Oxlade-Chamberlain played a pivotal role, scampering free on the right flank and getting a cross in before Ashley Cole could intercept, but there was still an awful lot for Gervinho to do as he controlled the ball, turned sharply and fired a shot high past Petr Cech and into the net.

Arsenal had probably done enough to deserve parity, and both sides probably went in at half-time part relieved and part-frustrated. Two defences that had been all but impenetrable in the league thus far this season were both looking shaky.

Torres, buoyed by his goal, was proving a real handful, and when he dropped deep again to pick up a pass early in the second half, Vermaelen followed him and clattered through the Spaniard to earn a booking.

The punishment was increased moments later when, from the resulting free-kick, Mata’s left-footed curler was allowed to travel into the six-yard box and all the way into the net with the aid of the faintest of touches from Koscielny.

Arsenal were left to chase the game again, and Wenger must have been tearing his hair out in the dugout. Steve Bould no longer has that option but a frown creased his brow – the defence that had conceded just two goals in five league games had gifted as many goals in the space of half an hour.

Arsenal had 35 minutes to salvage their unbeaten record, and certainly did not want for trying with Gervinho doing plenty of running up front but getting scant support from a disappointing Podolski and a largely ineffective Oxlade-Chamberlain.

Chelsea were happy to sit back and hit Arsenal on the counter, and the excellent Hazard looked very capable of doing so, although Torres wasted a couple of openings by being too easily dispossessed. At the other end Podolski saw his header clawed away by Cech, but while it looked spectacular it was a fairly comfortable save.

Cazorla was still attempting gamely to find a way through the blue back line, and Wenger made his decisive change midway through the half when he sent on Theo Walcott and Olivier Giroud in place of Podolski and Ramsey.

The Gunners were to fashion one great chance to make it 2-2, and it fell to Giroud. The Frenchman had opened his account for the club in midweek against Coventry, but had also missed a penalty.

And his difficult start to life at the Emirates looks set to continue after he was put through by Cazorla, but after rounding Cech could only find the side-netting.

That was to prove Arsenal’s last chance, and Chelsea celebrated in style at the end. It may still be early days, but capital’s title challenge looks most likely to come from west London again.

Arsenal: Mannone, Jenkinson, Vermaelen, Koscielny, Gibbs, Arteta, Diaby (Oxlade-Chamberlain, 18), Ramsey (Walcott, 67), Cazorla, Podolski (Giroud, 67), Gervinho.

Subs not used: Martinez, Mertesacker, Andre Santos, Djourou,

Chelsea: Cech, Ivanovic, Terry, David Luiz (Cahill, 82) Cole, Mikel, Ramires, Mata (Bertrand, 85), Oscar (Moses, 73), Hazard, Torres.

Subs not used: Romeu, Lampard, Turnbull, Azpilicueta.

Referee: Martin Atkinson

Attendance: 60,101