Arsenal boss Arsene Wenger expects the club's Champions League fate to be decided at home.
The Gunners beat Udinese at the Emirates in a qualifier for the competition, and then impressed in a 1-1 draw at Borussia Dortmund in their first Group F game.
Whilst the Frenchman was delighted with the result, he recognises that winning games at the Emirates will be crucial to the team's qualification, ideally in top spot.
"In the Champions League, you need 11 points to qualify (from the group stage) - that means you have to take nine at home and two or three away," he said after yesterday's 3-0 Barclays Premier League win over Bolton.
"We got an interesting point in Dortmund and we know after if we do well at home, then we will qualify."
Robin van Persie echoed the sentiments of his manager, and is expecting his teammates to help build on the point picked up against the Bundesliga champions last time out.
The skipper scored his 100th goal for the north Londoners in their weekend victory, and will be hoping to add to that total against Olympiakos on Wednesday night.
"We achieved a good result in Dortmund, even if their late goal might make that sound a bit strange. They are the German champions and their running and fitness was phenomenal," said the Dutchman.
"You could see we found it difficult to string passes together and it was clear we were playing against a top team.
"Looking at the situation as a whole, they really pushed us to the limit, so it is a good result and a decent start in the Champions League."