Improved Azarenka ready for Serena
Victoria Azarenka has warned Serena Williams she is a better player now than when she pushed the world number one all the way in the US Open final 12 months ago.
The pair will meet again in the title match in New York on Sunday after both secured comfortable wins in the last four.
As she has been all tournament, Williams was the most impressive as she powered past fifth seed Li Na 6-0 6-3.
The American has dropped just 16 games in six matches so far and will go into Sunday's match as a clear favourite.
But that was also the case last year and Azarenka very nearly won, the 24-year-old serving for the match before Williams edged to victory 7-5 in the deciding set.
The Belarusian, meanwhile, will take confidence from the fact she has won two of their three matches this season, including in Cincinnati last month.
Azarenka said of last year's final: "Mentally I felt like it was a great turning point for me. It was just really good experience.
"I feel like I'm a better player. I'm a more complete player. That's what you aim for after one year of work. So in terms of that, I'm pretty pleased."
Azarenka is one of the few players who can compete with Williams for power and athleticism on the court as well as fighting spirit.
But the second seed will need to have a much better day serving than she did against Flavia Pennetta, where 13 of the 18 games in Azarenka's 6-4 6-2 victory were breaks.
Azarenka said: "I'm happy I'm in the final. There are always things that can be better.
"I felt like the first set was a little bit tricky. The momentum wasn't there. I felt like I had great groundstrokes, just one shot wasn't working and it threw my rhythm a little bit off balance.
"Overall, just being able to pick up and raise the level in the important moments, that's what it's all about."
Williams has had a superb season and is looking to add a fifth US Open title to the French Open crown she won in June.
She said of her rivalry with Azarenka: "We always have really good matches. It's great to get to another final. She's a great player and she lifts her game whenever it counts. I think that's what makes the difference."
Williams had won her previous seven matches against Li but they had all been tight and the Chinesewoman had looked very good this tournament.
It was a surprise, therefore, that Li failed to win a single game in the opening set.
The fifth seed was spraying the ball all over the place, particularly with her forehand, while Williams was rock solid.
Remarkably, it was the world number one's third straight 6-0 set after she denied Carla Suarez Navarro even a game in the quarter-finals.
The second set was a lot more competitive, with Li briefly leading after breaking Williams' serve for 2-1.
But she could not back it up and the match only really reached the level of drama that had been expected when Williams was on the verge of victory.
Six times Li saved match points to force the American to serve it out, but she clinched her seventh opportunity.
Williams said: "It was a good match. Li Na's such a great player. It was tough at the end, I got a little nervous but I was able to close it out finally."
Former French Open champion Li was disappointed that nerves had got to her.
She said: "I should not be nervous because it's not the first time I've played in the semis.
"But when I walked to the court I was feeling the court was so big. My side was feeling like a football pitch. Serena's side was feeling like a table tennis table.
"Today it didn't matter who the opponent was. The problem was myself."
The crucial moment in Azarenka's victory over Pennetta came at the end of the first set, which the second seed finally clinched on her sixth opportunity.
It has nevertheless been a superb tournament for 31-year-old Pennetta, who missed the US Open last year after having wrist surgery that kept her out for six months.
Her ranking will climb from 83 to close to the top 30, and she said: "I'm really happy about the tournament, about how I played, the matches I won, everything.
"Today I lost but I lost against the number two in the world. I tried my best. I think I fought really well."