
The Polish driver, who earlier in the season missed a race after a horrific accident, needed one minute 22.390 seconds for the 4.384 km course, beating Ferrari drivers Felipe Massa and Kimi Raikkonen into second and third place.
Championship leading Lewis Hamilton and Fernando Alonso in a McLaren-Mercedes had the fifth and fourth-fastest time respectively, while Kubica's team-mate Nick Heidfeld was sixth fastest.
Hamilton leads the standings ahead of the 11th race of the 17-race season with 70 points, two more than his team-mate Alonso. Massa is third on 59, while Raikkonen has 52.
DPA