Although it also comes down to goal difference, which favours Swansea, Tremmel is looking for a positive performance in order to make sure they get through to the knockout phase.
"Qualification is in our hands, and that's very important," he told the South Wales Evening Post.
"Of course, it also depends on how Kuban do in Valencia, but we will only be concentrating on our match.
"We want to qualify for the next round by getting a good result in St Gallen.
"It won't be easy as it proved when we played them at the Liberty, but the whole squad is determined to go to Switzerland and get the result we need to get through.
"A positive result will give us a good feeling and a bit of momentum for the league game at Norwich on Sunday."
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