David Fuster appreciates that Olympiakos face a tough test against Arsenal, but believes they can claim a notable scalp.
The Greek champions are due at the Emirates Stadium on Wednesday for the second round of fixtures in this season's UEFA Champions League group stage.
Defeat to Schalke on Matchday One has left Olympiakos in need of points and a positive performance in North London.
Fuster feels they are capable of springing a surprise, with it possible that Arsenal's 2-1 derby defeat to Chelsea on Saturday could work in their favour.
"Arsenal are always a very difficult opponent in London, but Chelsea have shown us how to play to win the match. We know what we have to do," the Spanish midfielder told Sky Sports.
"Many times Olympiakos have tried to defeat Arsenal. This could be the moment to cause a surprise.
"We need to take something at the Emirates. No points from two matches would make things difficult for us."
Fuster added: "Arsenal's defeat to Chelsea could work for us or against us. They will want to respond, but they now have added pressure to please the fans. It is a tricky situation.
"Our ambition this season is to progress in the Champions League and we have always believed that is possible from day one."
What will be the outcome in the match Arsenal vs Olympiacos?