High-flying Casey Dellacqua has halved her tennis ranking since the start of the year as she eyes a spot in the Indian Wells Masters semi-finals.

This time she did it the easy way when American opponent Lauren Davis withdrew from their fourth round clash citing a stomach virus, but after coming through two qualifying matches just to make the main draw the 29 year-old will take the wins any way they come.

After starting the year ranked 130 in the world, Dellacqua has shot up the rankings to No.78, largely off the back of a fourth round appearance at the Australian Open.

And with her last eight spot at Indian Wells, where she will meet Romanian sixth seed Simona Halep, she’s expected to climb to the cusp of the top 60.

Dellacqua had reached a career-high No.38 in the world in 2008 before being sidelined for the best part of two years with foot and shoulder injuries.

In other women’s quarter-finals action Jelena Jankovic will play second-seeded Agnieszka Radwanska after the Serb ended a five-match losing streak against Caroline Wozniacki.

Jankovic, seeded seventh, defeated 10th-seeded Wozniacki 6-3 6-1 in a battle of former world number ones.

In a rematch of the 2010 final in the California desert won by Jankovic, the seventh-seeded Serb showed no sign of the back trouble that required several visits from the trainer during her third-round victory over Magdalena Rybarikova on Sunday.

Radwanska reached the quarter-finals with a 7-5 6-3 victory over France’s Alize Cornet.

Top seed Li Na of China advanced to the quarter-finals with a 6-1 6-4 victory over Canada’s Aleksandra Wozniak.

Australian Open champion Li lined up a rematch with the woman she defeated in the final at Melbourne, Dominika Cibulkova, who beat eighth-seeded Petra Kvitova 6-3 6-2.

Li steamed through the opening set against Wozniak in 32 minutes, but needed another hour and 11 match points to finally put her away.

Cibulkova defeated eighth-seeded Petra Kvitova 6-3, 6-2.

Italian qualifier Camila Giorgi, who shocked defending champion Sharapova in the third round, couldn’t maintain her momentum, falling 6-2 6-1 to compatriot Flavia Pennetta.

Halep reached the last eight with a 6-2 1-6 6-4 victory over rising Canadian star Eugenie Bouchard.