Roger Federer celebrates during the trophy presentation after defeating David Ferrer on day seven of the Western and Southern Open tennis tournament at Linder Family Tennis Center, Cincinnati, Ohio, Aug 17, 2014. [Photo/Agencies]

Ivanovic was treated for a stomach ailment during her nearly 3-hour win over Maria Sharapova in the semifinals Saturday night. She didn't have much left against Williams, who dominated with her serve.

Williams had 12 aces. "Only?" Ivanovic said. "It felt like way more."

The only other event that Williams had played six times without a title is Sydney. She finally got her win in Cincinnati with the help of a favorable matchup. Williams is 7-1 in her career against Ivanovic, the only loss coming at the Australian Open this year.

Although their last three matches have been close - all going three sets - this one was one-sided after the first few games.

"I felt like she was dominating," Ivanovic said.

Williams developed a stiff back that limited her serve in the semifinals Saturday night. She moved stiffly at the start Sunday, double-faulted in the first game and was broken - an ominous sign. But she started moving better and took control with her serve, pulling even at 3-3. She clinched the set when Ivanovic double-faulted twice in a row.

The back problem came into play in the second set. Williams winced after a serve in the opening game and arched her back. She stretched her back a few times between points and played through it.

"I felt it a little bit in the second, but I just was so excited for this final and to be in the final," she said. "I just really felt like I had nothing to lose. So I was able to relax."

Despite the loss, Ivanovic will move back into the top 10 in the WTA rankings with her strong showing in Cincinnati.

"It's the biggest final I've been in in a while. It feels good to be part of it," she said. "There are still a few points in my game that I feel I need to work on for the US Open and also for the end of season. Definitely exciting times."