Defending champion Agnieszka Radwanska was unseated in Tokyo today as Nadia Petrova beat her in the final of the Pan Pacific Open.

In a game that saw the momentum ebb and flow from one side of the court to the other, Petrova took the first set to love, surrendered the second to one and then took the match 6-0 1-6 6-3.

The decider was the most competitive of the three, with the match in the balance until Radwanska, the third seed, twice double faulted to let Petrova in.

She duly served out for the match, winning with a smash and adding Radwanska to her scalps for the week.

The Russian has now beaten Radwanska, Sara Errani and Sam Stosur on her way to the title, which is the 12th of her career.