Victoria Azarenka defeated Serena Williams in a three-set thriller to reach the US Open final on Thursday. The unseeded Belarusian came from behind to overcome Williams, seeded third, 1-6, 6-3, 6-3 in 1hr 56min under the roof of Arthur Ashe Stadium. Azarenka will now play Naomi Osaka of Japan in Saturday's final. pdh/rcw