Mauricio Pochettino believes it is important for Tottenham to get their Champions League campaign underway so they can "repair the damage" done by their defeat in the final last year.
"There's been a long period after the final in Madrid and, to be honest, I was thinking a lot during the summer," he said.
"To lose the final is always so painful because you can't put out the feeling, and you need to wait to start again to repair the damage."
Pochettino knows his side are being written off as final contenders this season, but wants them to make a statement by getting off to a winning start and putting in a good performance in Athens.
He said: "No one is thinking or giving us chance to be a contender to be in the final in Istanbul this season. But that is normal. That makes it again very exciting, our run in the Champions League.
"A few months ago we played the final of the Champions League and of course [playing] Olympiakos is going to put us in this level of favourites.
"It is going to be a tough atmosphere. I respect the opponent and you need to show why you are favourites when you start the game.
"We are going to make some changes, for different reasons, but the focus must be in the performance and quality of performance."