Schwarzer had also deputised for Cech in Saturday's 2-1 Barclays Premier League defeat to Sunderland, and asked about stepping in against Atletico, the Australian said: "There is not much to think about and it is happening so quickly.
"I'm always prepared and I'm getting used to this whole thing about sitting out and being ready to play at the last minute.
"It is always a tough thing to do. But tonight, I didn't have a chance to really think about it - I just went out there and tried to do my job."
And asked how, given those problems, he saw the tie now, Schwarzer added: "It is very tough, but you have to take each game as it comes.
"We now have to think about a massive game on Sunday (against Liverpool in the league), and then it's the return leg."
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