The German side now have just two points from a possible nine in the group, but Schuster said that a win away to the Portuguese side would provide a big boost.
"I think we started well and in the first half we were dominant - we had clear chances even after making it 1-0, but in the second half we lost the control of the game," UEFA.com quotes Schuster as saying.
"Estoril scored their goal with their first chance, but even after that we had some big opportunities to win. However, it was not to be - we missed them - and in the end we only have one point to show for it.
"Of course we want to win in Estoril. Anything is possible, and if we do win there we will try to make best use of the chance we've given ourselves. We will go there, give our best and try to win."