The Gunners needed to better the 3-2 win achieved by the Greeks at the Emirates Stadium earlier in the campaign to qualify for the knockout stages of the Champions League, and they duly obliged by securing a 3-0 win in Piraeus.
When asked if he could see the Gunners progressing, the Czech goalkeeper said: "Well, we could!
"We were searching for it and we knew if we played our game, if we have a great team performance and great individual performances then we will have a chance, and we did say exactly that.
"The first goal was important because going 1-0 ahead, they knew that one goal would not take us through and were holding back as one goal can kill the game for them.
"So there was pressure from both sides and we managed to get the better side of that pressure ourselves. The second goal was obviously an important point in the game and we knew that we would be able to do it."
Olivier Giroud scored a hat-trick as the Gunners made it to the knockout stages of Europe's top competition for the 16th straight season.