It is a rematch of the 2012 U.S. Open final, which Williams won 6-2, 2-6, 7-5.
Williams is 66-4 this year with eight championships, including the French Open title. She is currently on a 16-match winning streak, having lost just 16 games en route to her seventh U.S. Open finals appearance. She's been ranked No. 1 for the last 30 weeks and is seeking her fifth U.S. Open title, having won in 1999, 2002 and '08 in addition to last year.
Azarenka, ranked No. 2, is also having a sterling year. She is 42-4 with three titles. Among those is her successful defense of her 2012 Australian Open championship.
While she's just 3-12 lifetime versus Williams, she is 2-1 against her in 2013. Azarenka won in the finals at Doha and Cincinnati and Williams took the title match in Rome.
"Both matches she played really well," Williams said after her semifinal win Friday. "I let myself down at opportunities and I have to take them because she is always pumped up and she does really well.
"I definitely feel like when she plays me she plays her best, by far. I've seen her play against other players and when I play her I'm playing a totally different player. Obviously she brings her best game when she plays against me."
Williams has played more consistently at the U.S. Open, sweeping through her first six matches all in straight sets. She had a 24-game winning streak running from her fourth-round match through a 6-0, 6-0 pasting of Carla Suarez Navarro in the quarterfinals and the first seven games of a 6-0, 6-3 decision over fifth-seeded Li Na in the semifinals.
Azarenka, who opened her tournament with a 6-0, 6-0 win, twice dropped first sets but took her quarterfinals and semifinals in straight sets. Although the semifinal win against Flavia Pennetta was a up-and-down affair in which saw 13 breaks -- eight by Azarenka -- in the 6-4, 6-2 Azarenka win.
"You've got to fight," Azarenka said of playing Williams. "You've got to run. You've got to grind. And you've got to bite with your teeth for whatever opportunity you have out there.
"She's obviously an amazing player. She's the greatest player of all time."