Severin Freund was second after a 134.5m effort.
"The first day went pretty well for me, I had two good jumps," said Prevc.
"Tomorrow I hope that Severin and I won't fall. There are many things, that can decide the 4-Hills-Tournament.
"Every jump counts and there are a lot of favourites. I feel the pressure, but this helps me to focus."
Last season's overall World Cup winner Freund talked up his hopes of being the first German 4-Hills winner since 2002.
"I think it would be a brave guess to predict who's the favourite after one jump on a day like this," he said.
"I have to show two good jumps tomorrow. Today I was pretty close. And then you also need some luck. I think that tomorrow's result won't be decisive."