With the sun only occasionally poking through overcast skies, Finland's Bottas posted a fast final lap to turn in a best time of 1 minute 09.848 seconds, besting Hamilton by 0.050 second.
Williams teammate Felipe Massa was third and Daniil Kvyat of Torro Rosso fourth ahead of Rosberg, who was 0.151 second off the pace, as six tenths of a second covered the top eight drivers.
Sergio Perez of Force India went wide off one turn and saw his car briefly go airborne on Saturday before recovering.
Hamilton had been comfortably quicker than Rosberg in free practice on Friday, when the two Mercedes were the only cars to lap in under one minute 10 seconds. The Briton is 22 points behind Germany's Rosberg after seven races.
Hamilton has won four races to Rosberg's two so far this season, but has also suffered two costly retirements.
Qualifying for Sunday's Grand Prix, the first in Austria in 11 years, starts at 1200 GMT.
(Reporting by Michael Shields; editing by Sudipto Ganguly)
Share
