Melbourne: World No.1 Serena Williams survived a tough opening set from No. 5 seed Maria Sharapova to cruise into an 18th straight win over the Russian and reach the semifinals of the Australian Open, here on Tuesday.

Sharapova came out firing to start, taking an early 2-0 lead on Australia Day, but Williams worked her way into the match in style, saving break points at 4-4 and winning seven games in a row at one stage. Williams finally won 6-4, 6-1. Up next for the World No.1 is No.4 seed Agnieszka Radwanska.

Looking to tie Steffi Graf's record of 22 Grand Slam titles, Williams is also after a seventh Australian Open title, her first coming back in 2003 to complete her first Serena Slam.

Meanwhile, Radwanska booked her spot in the Australian Open semifinals for the second time, winning over Carla Suárez Navarro 6-1, 6-3 in the first match of the day on Rod Laver Arena.

Meanwhile, in the men’s section, Milos Raonic held his nerve despite a spirited comeback by fourth seed and 2014 champion Stan Wawrinka on Monday. Raonic, the No. 13 seed, hit 82 winners, including 24 aces, to beat Wawrinka 6-4, 6-3, 5-7, 4-6, 6-3 on Rod Laver Arena in three hours and 44 minutes.

In another match, Andy Murray extended his winning streak against Australians to 17-0 on Monday night when he defeated No. 16 seed Bernard Tomic at the Australian Open. Second seed and four-time finalist Murray defeated the home hope 6-4, 6-4, 7-6(4) in two hours and 30 minutes for a place in his seventh straight quarter-final at Melbourne Park.