Arsenal's defense had been solid through five games this season, but on this occasion, Koscielny was poorly positioned and Oxlade-Chamberlain was left trying to mark the much bigger Luiz.
The goal certainly opened the game up, which was just what the doctor ordered as far as the 60,101 spectators were concerned. Arsenal went looking to get back on level terms and did so just two minutes before the break.
Mikel Arteta sent Oxlade-Chamberlain away down the right. Looking up, the England youngster spotted Gervinho and crossed along the ground, right through former Arsenal defender Ashley Cole. The Ivorian controlled with one touch, turned smartly and rifled the ball into the roof of the Chelsea net.
Chelsea Forges Ahead
The second period was only eight minutes old when the visitors again took the lead.
It all started once again from a professional foul by the Arsenal skipper. This time his victim was Torres and Vermaelen received a yellow card for his trouble.
The offence was committed a similar distance from goal but this time to the right rather than the left of center. Mata again took responsibility for delivery into the box.
His left footer beat everyone with the exception of Laurent Koscielny who just got a knee to the ball and helped it past Mannone.
Arsene Wenger's team worked hard to try and fashion an equalizer but were frankly below par in the final third. Nonetheless, they did create three or four good chances and really should have converted at least one of them to earn the point.
Just six minutes after Chelsea's go-ahead goal, Kieran Gibbs chipped the ball nicely into the area for Lukas Podolski, but the German's accurate header brought the best out of Cech who managed to turn it wide of the post.
At the 79-minute mark, an attempt by substitute Giroud took a big deflection off Luiz and although Cech found himself moving away from the ball, managed to get one of those big hands to it and somehow push it wide.
Four minutes from the end of normal time Koscielny hit the post with a header from Santi Cazorla's free kick, but the best chance of all fell to Olivier Giroud in stoppage time.
The out of form French striker finally opened his Arsenal account in the League Cup in midweek and had an opportunity here to make a name for himself in an Arsenal shirt. Following a surge forward by Oxlade-Chamberlain, Giroud was put through on the left side of the area but hit the side netting after rounding Cech.
Arsenal have lost for the first time this season, but still appear to be in much better shape than they did this time last year. The loss of Diaby was a severe blow for Wenger in this game and of the three Arsenal substitutes, only Oxlade-Chamberlain really looked the part with both Theo Walcott and Giroud conspicuously failing to influence the final result of the match.
"I feel we played against a good team, but we gave the game away," Wenger said on arsenal.com. "They had three shots on target and scored two goals, from soft set-pieces.
"Defensively we were just not at the level you have to be in a game like that, which is where we were punished today."
This was a thoroughly professional performance by the European champions who can now prepare for Champions League action knowing they're at the top of the tree going into the next round of Premier League games.
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