Schwarzer was unexpectedly called into action in the 18th minute of the UEFA Champions League semi-final first leg at Vicente Calderon after Petr Cech fell awkwardly in an aerial challenge and suffered a suspected dislocated shoulder.
The 41-year-old coped well under pressure, as Atletico dominated possession against a Chelsea side content to get men behind the ball and defend from deep.
Cech's injury was one of a number of setbacks for the London club ahead of the second leg next week, with captain John Terry also taken off injured with an ankle problem, while Frank Lampard and John Obi Mikel will be suspended for the return clash after picking up yellow cards during the second half.
According to manager Jose Mourinho, Cech is out for the rest of the season and Terry may only return if they reach the UEFA Champions League final, .
On being called into action from the bench, Schwarzer explained it was part and parcel of being a goalkeeper.
"There's not much to think about," he told ITV."It happened so quick.
"It's a tough thing to do, but I had to go out there and try to do my job.
"Everyone was right up for it, which you would expect. We knew if we matched their determination our quality would come through.
"Okay, we didn't create many chances but it was a good performance."
Defender Cesar Azpilicueta, who made a brave block from Diego Costa in the first half, echoed the sentiments of his Chelsea team-mate.
"It's a positive result," he said. "We knew it would be a difficult atmosphere.
"We fought hard and tried to keep the ball but the important thing is that we have the second leg at home.
"The players we will be missing are very important but we will fight to win."
The double injury setback to Cech and Terry comes as a huge blow for Mourinho and his men, who face leaders Liverpool in a potential Premier League title decider at Anfield on Sunday before the return leg against Atletico at Stamford Bridge three days later.
"Petr Cech's season is over," confirmed the Portuguese. "For John, we will have to play the final for him to play again.
"It wasn't the result I wanted before kick-off, but I didn't want to start the second leg a goal down either.
"A goalless draw is not a positive result for a team playing the second leg at home, but it'll do.
"Atletico were frustrated, whereas usually they are the ones who frustrate other teams.
"My side had a solid performance, we played in a way that irritated them."