Serena wins the chance to prove her point

Serena Williams said before the start of the Australian Open that she felt like the world No 1, even if the rankings told you that Jelena Jankovic was the best player on the planet.

On Saturday the 27-year-old American will have the chance to reinforce her point when she takes on Dinara Safina in her fourth Melbourne final. The world No 1 position will be at stake, with the winner certain to overhaul Jankovic in next week's updated ranking list.

Williams, the No 2 seed, and Safina, the No 3, both won their semi-finals here today without dropping a set. Williams beat Elena Dementieva, the No 4 seed, 6-3, 6-4, while Safina beat Vera Zvonareva, the No 7, 6-3, 7-6. With the temperature soaring above 40C for the second day in succession, tournament organisers again invoked their "extreme heat policy" and shut the roof over Rod Laver Arena for both matches.

Dementieva had come here as the game's form player, having gone unbeaten in 15 matches after winning the titles in the warm-up tournaments in Auckland and Sydney. The Olympic champion had also won her three previous matches against Williams, including a 6-3, 6-1 drubbing in Sydney three weeks ago.

From the start it was clear that the match would be tight. Both players struck the ball with great strength from the baseline and the rallies were often brutally long. Williams might have the more powerful frame, but the slender Dementieva also gives the ball a mighty clump.

The key difference was on serve. Williams hit 10 aces and no double faults, Dementieva only three aces and eight double faults. The serve has always been the Russian's biggest problem and even if it is less of a weakness than in the past you sense that it remains a fault line that can open up under pressure.

It took 16 minutes to complete the first two games and there was only one break of serve in the first set. Dementieva was broken in the eighth game and Williams, who won 16 of her 17 first-serve points in the first set, served out to take it in 44 minutes.

The first game of the second set lasted an exhausting 14 minutes as Dementieva clung desperately to her serve. When the Russian won the next two games it seemed that the match might be turning around, but Williams is the comeback queen. In the fifth game the American fell heavily after being wrong-footed but still broke serve and was soon level at 3-3.

Dementieva broke again to lead 4-3, but with that her resistance ended. When Williams served for the match she made no mistake, two aces helping her complete victory in an hour and 39 minutes.

Safina never had things all her own way in the other semi-final as Zvonareva gave a solid display in her first appearance at this stage of a Grand Slam tournament at her 25th attempt. The 24-year-old Muscovite has built her ranking through success in lesser tournaments, having won in Prague and Guangzhou last year and finished runner-up in six other events.

Zvonareva lost her serve three times in a 39-minute first set in which Safina consistently forced the pace. The world No 7 served for the second set at 6-5 but promptly dropped her serve to love. The tie-break was close, but Safina won it 7-4, clinching victory with a lovely forehand cross-court pass.

Safina has lost five of her six matches against Williams, who beat her last year in the semi-finals of the US Open and at the season-ending Sony Ericsson Championships. The Russian's only victory came on clay at Berlin last year.

Williams has won on all three of her previous appearances in the final here, in 2003, 2005 and 2007. She is in much better shape than she was two years ago, when she won the title as the world No 81, which made her the lowest ranked player to win a Grand Slam tournament for 29 years.

Safina, 22, is one of the game's most improved players. Last year she reached the final of the French Open, where she lost to Ana Ivanovic, and consistently good performances have taken her to No 3 in the rankings. Winning on Saturday would take her to No 1 for the first time, but Williams presents a formidable obstacle.