Arsenal manager Arsene Wenger acknowledged his team have a big hurdle to overcome on Wednesday if they want to advance to the last 16 of the Champions League, but the Frenchman is confident.

The English Premier League side have to beat hosts Olympiakos by at least two clear goals -- or beat them by one but by scoring at least three times -- to go through.

But the in-form hosts are unbeaten in their domestic league and beat Arsenal 3-2 at the Emirates Stadium in September.

"If you want to jump a hurdle, you do not think what happens if you miss it. We have a history of positive results, we have won everywhere in Europe and we know we can do it," said Wenger at Tuesday's press conference.

Last season against Monaco in the last 16, Arsenal lost 3-1 at home but could only win 2-0 away as they crashed out.

"We can learn from that. The game we played was very positive, maybe we rushed it in the last 10 minutes. That's what we can learn. I believed we played quite well in that game," Wenger recalled.

The Arsenal mentor said that a quick first goal against Olympiakos will be the key to success, and to avoid breaking their 15-year streak of reaching the knock-out rounds.

"As long as you don't win any competition, it is bad. On the other hand, we have got out of the group stage 15 times consecutively, so you can say that's a good habit," he added.

Wenger said he hoped Olympiakos woiuld be feeling the strain of trying to get out of the group.

"Let's not forget Olympiakos are qualified at the moment but they can lose what they have. That can create a fear factor," said the 66-year-old.

Olympiakos coach Marco Silva admitted that he was surprised to see Arsenal struggling to qualify at this late stage.

But he said the pressure is on the Londoners after they failed to breeze through the group alongside Bayern Munich, who have already secured top spot.

"Many thought during the draw for the group that the favourites for the top two spots were already decided. It is indeed rare to see an Arsenal team not being able to qualify early and this will add more pressure to them. We do not feel pressure," the 38-year-old Portuguese coach said.

"As for us... we have a chance before our supporters to claim qualification against outstanding opponents."

"We won in London and will look to do the same here. Before the match in England everyone knew who was favoured. We overcame the odds and are looking to do the same here.

"With great respect and humility we will attempt to do something good. And of course under no circumstance are we underestimating our opponents."

Nigerian forward Brown Ideye who last season played for West Bromwich Albion and joined Olympiakos in the summer, believes that his team has to score goals to keep Arsenal at a distance.

"We have to win and they have to score a lot of goals. We have to score goals in order to force Arsenal to score more goals. We have to attack and defend well. If we manage to score once then Arsenal must score many more goals, and this is pressure for them," the 27-year-old said.