Federer and history against Roddick

American Andy Roddick will need to reverse a dreadful big match record against world No2 Roger Federer  if he is to reach his first Australian Open final.

Roddick, the seventh seed, who is in his first grand slam semifinal in two years, has won just two of his 17 career matches against the Swiss great.

But of even greater concern is his record against the 13-time grand slam winner in the majors.

The pair have met six times in grand slam events, with Roddick managing to take a set from Federer in just two of those matches.

The last two of those were straight sets wins to the Swiss, in a US Open quarterfinal in 2007 and an Australian Open semifinal earlier that year, when Roddick notched just six games.

Federer comes into the match in superb form, having blitzed Argentina's Juan Martin del Potro 6-3 6-0 6-0 in a quarter-final, while Roddick outlasted defending champion Novak Djokovic, who retired from their match.

The two women's semifinals will also be played today.

American world No2 Serena Williams, chasing her fourth Australian Open crown, will meet Russian fourth seed Elena Dementieva.

The two women enter the clash coming off vastly different quarterfinal performances.

Williams came close to being defeated in straight sets by Russia's Svetlana Kuznetsova, before fighting back to win a three-setter, while Dementieva cruised past unseeded Spanish youngster Carla Suarez Navarro.

The other women's match is an all-Russian affair between Jelena Dokic's conqueror, world No3 Dinara Safina and Vera Zvonareva, who thrashed Frenchwoman Marion Bartoli in their quarter-final.

Meanwhile, Australia's Casey Dellacqua and Italian partner Francesca Schiavone meet Serena and Venus Williams in a doubles semifinal.

In the other semifinal, Slovakia's Daniela Hantuchova and Japan's Ai Sugiyama take on France's Nathalie Dechy and Italian Mara Santangelo.

-AAP