The 22-year-old slalom specialist was pushed in the quarter-finals and last four by Austria's Ricarda Haaser and Italian Irene Curtoni respectively.
She had to work even harder in the final, shaking off the Slovak by four hundredths of a second to clinch her 35th World Cup victory.
Shiffrin earned her first career World Cup win in downhill at Canada's Lake Louise earlier this month and also won the slalom for the second year in a row at Killington in Vermont.
The Pyeongchang Olympics in South Korea run from Feb. 9-25.
(Reporting by Karolos Grohmann; Editing by Toby Davis)