Reigning Grand Slam champions Serena Williams, Maria Sharapova and Victoria Azarenka are locked in a battle for the US Open title and the season's global bragging rights in women's tennis.

All three will try to claim the $1.9 million top prize and their second major title of the year in Saturday night's championship match at Arthur Ashe Stadium, where Williams has won three crowns and Sharapova took the 2006 title.

"I really want it bad. I'm going to do absolutely everything I have to and give it all," Azarenka said. "First time being in the US Open semifinals is incredible feeling for me."

World No 1 Azarenka, the top seed from Belarus, will face Russian third seed Sharapova in one of Friday's semifinals while US fourth seed Williams meets Italian 10th seed Sara Errani, the 2012 French Open runner-up in the other.

Azarenka has ensured she will be atop the rankings next week no matter who wins and enjoyed a season that included her first Grand Slam title at the Australian Open.

"Many people expected her to win a Grand Slam earlier than she did," Sharapova said of Azarenka. "She always had a solid game. She was always a little mentally fragile, felt like she would bang her racket and yell.

"But I think with age and maturing you learn so much by playing matches. You learn what helps you get motivated."

No top seed has won a Grand Slam since Williams at Wimbledon in 2010 and no US Open women's top seed has won since Justine Henin in 2007.

"I feel like I will never be satisfied," Azarenka said. "Even at the peak of my career now I want to do better. The ambitions are really high.

"(World No. 1) means a lot but it's nothing like lifting a trophy. It's just a number. It's a great achievement. It's something you work really hard for your whole life to be, but this will not compare."

Sharapova, who completed a career Grand Slam by winning her fourth major title at the French Open, will rise to second in the rankings next week.

"Maria is one of these players who will give it all no matter what the score is," Azarenka said. "She's always fighting and she's really tough mentally."

Williams, a 14-time Grand Slam champion, won the Wimbledon title and London Olympic gold medal and has hit an Open-best 41 aces with a serve that has overwhelmed rivals. A US Open title would make her the clear top woman of 2012.

"It's one thing to serve a big serve but it's another thing to do it consistently match in match out with the power and the strength," Sharapova said. "She finds corners extremely well but on a consistent level.

"If you are feeling confidence and that's working for you, I think all other pieces of the puzzle come together."