The first loss of the season, particularly when you could have easily avoided it, is never easy to take. However, Arsenal will have to move on quickly from the Chelsea defeat and look to get back their mojo against Olympiakos in the Champions League.
Arsene Wenger's team have made a bright start to European campaign, with their opening round Champions League victory away to Montpellier sure to stand them in good stead as they prepare to face the Greek side for the fifth time in three years.
On paper, the Gunners should walk away with victory, even if they are missing the services of powerhouse midfielder Abou Diaby. What will be more of a concern for the manager, though, is the situation with Mikel Arteta.
The Spaniard, who is carrying an ankle injury, missed training on Tuesday and is scheduled to have a test on Wednesday morning to see if he will be fit for the game or not.
One of Francis Coquelin, Alex Oxlade-Chamberlain and Aaron Ramsey should come in for the duo, with Santi Cazorla expected to continue in the advanced role. Arsenal were pretty sloppy at times against Chelsea, their recent good defensive form nowhere on view.
Wenger will be hoping the mistakes were just an aberration, but the Frenchman will be concerned about giving away three goals from set pieces in their last two English Premier League games.
Olympiakos will be well aware of what they will perceive as Arsenal's soft underbelly, and expect them to test the defense with long balls and free kicks every time they are given an opportunity, while the Greek side will definitely have plenty of men behind the ball while Arsenal are in possession.
"It will be particularly hard - Arsenal at home are very strong - but you can't give up on a game before you even start it," Olympiakos manager Leonard Jardim said. "We will try to enjoy the game and give a good account of ourselves.
"Arsenal are a particularly difficult team, very technical, and we will try to face them by being very compact. That's why we try to be very united - all the players together to decrease the chances of our opponents, just like we played against Schalke."
Even if Arteta might be a big miss, Coquelin should fill in nicely in the deeper defensive midfield role, while Ramsey is on a decent run of form. Oxlade-Chamberlain immediately looked like a better player when he switched to the middle of midfield when Theo Walcott was brought on in the game against Chelsea, and Wenger will be pondering on his best options against the Greek side.
Ramsey brings passing astuteness and vision, while Oxlade-Chamberlain has the ability to run through the middle at will and create havoc to the opposing defenses.
Olivier Giroud missed yet another chance against Chelsea last Saturday and the striker is in desperate need of a string of goals. Being it is a Champions League game at home, it will be interesting to see whether Wenger sticks to Gervinho as the center forward, or maybe brings in Giroud from the start to give the Frenchman a better chance of finding the back of the net, and also give the Gunners a physical presence.
If Gervinho starts up front, Oxlade-Chamberlain is most likely to begin the game on the right side of midfield, with a central midfield trio of Cazorla, Ramsey and Coquelin.
Lukas Podolski will be looking to get back on goalscoring terms, and the German international will again be most dangerous while linking up with Cazorla and Kieran Gibbs.
In the defense, Carl Jenkinson and Gibbs are automatic starters, while Wenger has another vital decision to make about his central defensive partnership.
Koscielny might have scored the equalizer against City, but the Frenchman was at fault for all three goals conceded from set pieces. Per Mertesacker has had a stellar start to the season, and it is likely the German will come in for the French international, to partner Thomas Vermaelen.
Expected line-ups: Arsenal: Mannone, Jenkinson, Mertesacker, Vermaelen, Gibbs, Coquelin, Ramsey, Cazorla, Podolski, Oxlade-Chamberlain, Gervinho.
Olympiakos: Carroll, Greco, Contreras, Manolas, Holebas, Maniatis, Siovas, Ibagaza, Fuster, Mitroglou, Machado.
