Skiing on their home-country snow at Zauchensee, Goergl and Fenninger topped third-place Maria Hoefl-Riesch of Germany.
Goergl's mistake-free run and winning time of 1 minute, 47.45 seconds put her in first place in the overall women's World Cup standings ahead of second-place Hoefl-Riesch.
"I had a blast on the [hill] today and it's just great it ends up with a victory", said Goergl, whose run late in the day knocked teammate Fenninger out of first place.
Tina Weirather of Lichtenstein placed fourth, followed by Austrian Nicole Hosp in fifth place.
"I was one mistake away from being in the top ten and having a really good result, so it's really positive," said Mancuso, who missed the previous three World Cup downhills in order to train in the United States. "We have two more races that hopefully have good training runs that I can get feeling a lot better on my equipment and I'm definitely more positive."