Second seed Jelena Jankovic held the No 1 ranking for one week earlier this year and says she is ready to take her game to the next level when she squares off against fifth seeded Russian Elena Dementieva.

"I am going to do whatever it takes to win all these matches," the 23-year-old Serbian said. "It would be nice to regain the No 1 but I am playing in a Grand Slam and my goal is to win a Grand Slam."

Beijing Olympic silver medallist Dinara Safina and American fourth seed Serena Williams, who won an epic battle against sister Venus in the quarter-finals, face off in the other semi-final.

Heading into the 2008 US Open, five players had a chance of knocking Ana Ivanovic out of the top spot and with Ivanovic getting eliminated early it opened the door even wider.

Jankovic has advanced far into just about every tournament this year including the semi-finals of the French Open where she stumbled down the stretch and lost to Ivanovic.

This will be her eighth career meeting against Dementieva with Jankovic having won four.

Dementieva has three wins including a 6-2, 2-6, 6-3 win in their last meeting earlier this year in Berlin.

"She's (Dementieva) a tough player," said Jankovic, who becomes No 1 if she wins the US Open. "She's very solid. She moves great.

"I have beaten her I don't know how many times and I think I beat her here two years ago in the quarter-finals.

"I would love to take another step and reach my first final of a Grand Slam and then play on Saturday."

Like Jankovic, Dementieva is looking for her first Grand Slam title and if it comes this weekend she would also be number one. She came into the US Open on a high after winning the gold medal in singles at the Beijing Olympics.

The 26-year-old Russian hasn't skipped a beat at Flushing Meadows, making it to the semis without dropping a set.

Dementieva, who needs to reach the final to have a chance at being number one, said she plans to go on the attack against Jankovic.

"She is going to play everything back," Dementieva said of Jankovic. "She moves unbelievably well on the court and she is pretty solid on the baseline.

"You have to go on the court and create something. There is no way you can wait for a mistake or just be defensive on the baseline. You really need to do something."

Serena Williams held the top spot for 57 weeks back in 2003 and doesn't mince words when it comes to predicting her chances of regaining the crown.

"Believe me, I am going to be number one sooner or later.

There's no way I'm going to give up this gig any time soon," said Serena who needs to win the title to be number one.

Williams has walked over the competition without dropping a set. But she didn't play a top 30 player until the quarters when she faces sister Venus for the 17th time in their careers.

The match featured some dynamic rallies, crisp volleys and precision passing shots but Venus squandered 10 set points, allowing Serena to rally in both tie-breakers and snatch a 7-6 (8/6), 7-6 (9-7) victory.

Serena has a career 3-1 record against Safina who needs to win the title and have Jankovic lose in the semis to seize the top spot.

Their last meeting was in Berlin earlier this year where Safina won 2-6, 6-1, 7-6 before going on to take the title.

Safina is trying to make a name for herself at this year's US Open. Her big brother, Marat, won his first Grand Slam title at the 2000 US Open and she would like to follow in his footsteps.

She expects Serena to try to run down every ball.

"Serena fights to the last," Safina said. "She moves very good and she can hit the ball from any position on the court.