* Azarenka claims third title of the year
* Cincinnati still on Williams' 'bucket list' (Adds quotes)
CINCINNATI, Aug 18 (Reuters) - Victoria Azarenka won a showdown between the world's two top players by beating number one Serena Williams in a three set 2-6 6-2 7-6 thriller in the final of the Western and Southern Open on Sunday.
For two hours and 30 minutes, Azarenka and Williams engaged in a seesaw battle before the Belarusian finally clinched the victory, winning a nervy tiebreak 8-6 to prevent the American from ticking a Cincinnati win off her 'bucket list'.
"Obviously, a big win. It was a great match," Azarenka told reporters. "Really, really pleased with the way I pulled it out. It was a great battle.
"There were no giveaways. It was pure fight."
In a career that has generated 54 singles titles, including 16 grand slams, Williams had won just about everything there is to win in her sport - but not Cincinnati, one of the WTA Tour's most prestigious tournaments.
Cincinnati will remain a hole on her resume for at least another year after Azarenka answered the challenge by claiming just her third win in 15 attempts against the 31-year-old American.
Williams came into the contest with a chance to pass several career milestones beyond a first Cincinnati win but failed to secure any of them.
It was only the second time in 10 finals this season that Williams had failed to walk away with the trophy, while a victory on Sunday would have moved her up a notch on the career wins list into a tie for seventh place with Britain's Virginia Wade and compatriot Lindsay Davenport.
But the day belonged to Azarenka, who bagged her third title of the year and 17th of her career.
"We go against each other really tough, so I think, yeah, it's a good rivalry," said Williams. "I'm number one, she's number two so we have that rivalry which consists of meeting in the final, which makes it even more so exciting.
"I personally was thinking it is a good rivalry and it's good to have someone out there that can play hard and fight so tough.
"She's a great player. There's a reason why she's winning grand slams and doing so well."
A marquee final featuring the world's number one and two ranked players initially failed to deliver the high-quality spectacle expected from two women who have captured five of the last seven grand slams.
Azarenka, who struggled with her serve against Jelena Jankovic in the semi-finals and held just three times, opened the match with two double faults to hand Williams the early break.
Williams continued her assault on Azarenka with another break at 4-1 that left the Belarusian waving her racket in anger.
"I felt like my energy wasn't maybe there 100 percent at the beginning but that's what the match is about," said Azarenka. "It goes up and down, and you battle against somebody and you have an edge or then you don't have an edge.
"That's what is exciting about that to try to take your opponent to that place where they don't feel at their best."
In the second set it was Azarenka who had Williams talking to herself as she turned the tables on the muscular American by breaking her three times to level the match.
In the third, Azarenka and Williams finally produced the tennis and edge-of-your-seat drama that fans had come to see, twice trading breaks to send the set into a tiebreak.
With the title on the line, the quality of shots and effort sky-rocketed at both ends of the court before the contest ended with Williams's forehand into the net. (Editing by Nick Mulvenney)