The Romanian Simona Halep, 24, won 7-6 (7-2), 6-3 to claim her third throne title of the year over American Madison Keys.
The Romanian overcame Angelique Kerber in three sets, while Keys booked her place in the final with a comfortable victory over the unseeded Kristina Kucova.
As for Halep, she needed 100 minutes to overcome the No 2 seeded German 6-0 3-6 6-2.
However, the world number five was unable to add a second title as she and compatriot Monica Niculescu were beaten by Russian duo Ekaterina Makarova and Elena Vesnina in the doubles final.
Makarova and Vesnina, who will represent their country at the Rio Olympics, won 6-3, 7-6 (7-5).
It was a different matter in the singles where fifth seed Halep eventually breezed through a tie-break against the 21-year-old American after a first set that saw eight breaks of serve.
Halep, who also beat Keys in the fourth round at Wimbledon, broke again in the second set and never looked troubled thereafter.