Federer, Williams, Djokovic advance to Aussie semis

Serena Williams beat Maria Sharapova for the 18th time in a row to reach the Australian Open semi-finals.

The defending champion, seeded number one and chasing a 22nd Grand Slam title, saw off fifth seed Sharapova 6-4 6-1 at Melbourne Park.

The world number one, who has not lost to Sharapova in 12 years, now faces fourth seed Agnieszka Radwanska.

In the men's draw, Roger Federer and Novak Djokovic will meet in the semi-finals after straight-set victories.

Federer, a 17-time Grand Slam champion who has won the tournament four times, beat Tomas Berdych 7-6 (7-4) 6-2 6-4, while top seed and defending champion Djokovic saw off Japan's Kei Nishikori 6-3 6-2 6-4.