The Blues took a 2-0 lead against Juventus at Stamford Bridge in their opening group stage encounter last season, only to see the Italians come storming back to earn a draw in a result that later proved decisive in their early exit from the competition.
And Cech believes the incident must serve as a reminder for his side as they prepare to face the team they eliminated in the semi-finals of their Europa League-winning run.
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"But that this the way, there are no ifs and buts, you have to get more points than the other teams and we didn't do so.
"Last season we didn't do well, that was the simple thing. If you do well you obviously qualify, if you don't do well then you can't qualify and those games we played last season in the group stage we were not playing well enough to win games.
"This is why Shakhtar and Juventus ended with more points than us, that was it. You have to make sure you win games at home, you win games away, and the group stage gets tougher and tougher every year because the teams are getting quality players as they want to improve every year, and you need to make sure you are ready."
Cech went on to share his pride at seeing the club of his youth, Viktoria Plzen, also competing in the group stage, despite their 3-0 loss to Manchester City on Tuesday evening.
"It is an exciting time for them and they did well to qualify," he added.
"For the people there it is great to see a big team from England and from Germany with Bayern Munich coming to their town.
"They played in the Champions League two years ago and they got some points so they qualified for the Europa League, so hopefully this time they can win enough points to carry on in the new year, it will depend on if they get more points than CSKA Moscow."