Ivanovic got by Williams 6-2, 5-7, 6-4 in a 2-hour, 19-minute final that gave Ivanovic her 13th WTA title and her first win since November 2011.
Williams, whose 44 WTA championships are second-most among active players [her sister Serena won title No. 58 Saturday in Brisbane, Australia], is 44-28 in finals. Saturday marked her first title match since she won at Luxembourg in October 2012.
Ivanovic won the first five games Saturday and worked her way to match point at 5-3 of the second set before Williams fought back with four straight game wins that evened the match.
Ivanovic opened the third set with a break at love and fought off break chances in her next two service games before closing out the tournament.
It was just the second time in 10 meetings that Ivanovic defeated Williams.
Ivanovic's first-place check totaled $43,000 Saturday, giving her career winnings of more than $10.8 million. Williams has won just less than $29 million in her career after taking home $21,400 as the Auckland runner-up.