(Adds second set)
NEW YORK, Sept 8 (Reuters) - A battling Victoria Azarenka won a second-set tiebreaker 8-6 over Serena Williams to send the U.S. Open women's final to a third set.
After losing the first set 7-5 on a windblown Arthur Ashe Stadium court, Azarenka found herself down 4-1 with defending champion Williams serving.
The determined Belarussian, who had double-faulted three times in losing her serve in the fifth game, broke the big-serving American three times to take the set to a tiebreaker.
Williams, who twice served to win the match, double-faulted on the last point of the game that made it 6-6 and forced the tiebreaker.
World number one Williams rushed out to a 3-1 lead in the decider, but the second-seeded Azarenka won five of the next six points to take charge at 6-4 before taking the tiebreaker when Williams belted a backhand too long.
It was a title rematch between Williams and Azarenka, won last year by the American 7-5 in the third set. (Reporting by Larry Fine, Editing by Gene Cherry)