Top-ranked defending champion Serena Williams has advanced to a US Open final showdown with world number two Victoria Azarenka by defeating Chinese fifth seed Li Na 6-0, 6-3.
Williams will try to capture her 17th career Grand Slam title and fifth US Open crown on Sunday at Arthur Ashe Stadium in a rematch of last year's final, in which Williams downed Azarenka 6-2, 2-6, 7-5.
"I'm excited to be in another final," Williams said. "We always have really good matches. I look forward to it. She's a great player and she lifts her game when it counts. I think that's what makes the difference."
Two-time reigning Australian Open champion Azarenka, 24, ousted Italy's Flavia Pennetta in the other semi-final and beat Williams in last month's final at Cincinnati, but Williams still owns a 12-3 career edge on her Belarus rival.
"I'm so excited. It's been a long road to the final. It's an amazing feeling, to fight for the trophy," said Azarenka, a former US Open junior champion and mixed doubles winner.
Williams, also the reigning French Open champion, has not dropped a set in the tournament and has surrendered only 16 games in six matches.
At 31, the American would become the oldest women's champion in US Open history.
"I've been really focusing in my practices and working really hard," Williams said.
No matter how Sunday turns out, Williams and Azarenka will have combined to win six of eight Grand Slam titles over two years.
Williams won for the ninth time in 10 matches against Li, dominating from the start but struggling to close out the end, losing six match points on Li's serve in a penultimate game that lasted nearly 14 minutes.
I'm so excited. It's been a long road to the final. It's an amazing feeling, to fight for the trophy
"It was a good match. Li Na is such a great player," Williams said. "I got a little nervous there at the end but I was able to close it out."
Li, the 2011 French Open champion, sent a forehand wide off the net cord to surrender a break in the fourth game and she sent a backhand wide in the sixth game to hand Williams the first set after 29 minutes, having made 12 unforced errors and only one winner.
The end came after 87 minutes when Williams hit a service winner on her seventh match point chance, but the first on her serve.
In the other semi final, both players struggled to keep their serve on centre court with 13 breaks of serve in the 18 games, but Azarenka's power was too much for the enterprising Pennetta, who returned from a serious wrist injury to reach her first grand slam semi-final.
There were five service breaks in a row before Azarenka, the Australian Open winner, held to win the set after an intense battle where the unseeded, 31-year-old Pennetta saved five set points.
The second set followed a similar pattern, with three broken serves before Azarenka turned up the power, holding to go up 3-1 in the set and then breaking Pennetta, ranked 83rd in the world, with a powerful backhand winner.
Azarenka also struggled to make her serve count though, offering a glimmer of hope to the 31-year-old Italian when she went wide with a return on break point.
But once again Pennetta was unable to hold, twice finding the net to hand Azarenka the chance to serve for the game and despite a brave effort from the Italian, who produced a sizzling return down the line in the final game, Azarenka sealed the win with a well-placed forehand.