MELBOURNE, Australia -- Li Na advanced to the Australian Open semifinals with a 7-5, 6-3 victory over fourth-seeded Agnieszka Radwanska, ending the Polish player's 13-match winning streak to start the year.In a match featuring 10 breaks of serve -- six by Li -- the sixth-seeded Chinese player broke Radwanska's service in the sixth game of the second set without allowing her opponent a point.Serving for the match, Li fended off two break points before prevailing in 1 hour, 42 minutes.Li, a losing finalist here to Kim Clijsters in 2011 just before she clinched her only Grand Slam title at the French Open, will play the winner of Tuesday's later quarterfinal between Maria Sharapova and Ekaterina Makarova. Radwanska won tournaments in Auckland and Sydney ahead of the Australian Open.Unstoppable SerenaSerena Williams continued her run toward a third consecutive major title, beating Maria Kirilenko 6-2, 6-0 to reach the quarterfinals. Williams has lost only one match since her first-round exit at the French Open last year. Her 57-minute win extended her current winning streak to 20 matches. The 31-year-old can become the oldest woman to hold the world No. 1-ranking by winning her sixth Australian Open title. She next plays 19-year-old American Sloane Stephens, who reached the quarterfinals at a major for the first time with a 6-1, 3-6, 7-5 win over Bojana Jovanovski of Serbia.Azarenka moves onDefending champion Victoria Azarenka raced to a 3-0 lead in nine minutes and went on to beat Elena Vesnina 6-1, 6-1 in 57 minutes to advance to the quarterfinals. Azarenka will play Svetlana Kuznetsova in the quarterfinals on Wednesday.Roger goes forwardRoger Federer overcame big-serving Canadian Milos Raonic 6-4, 7-6 (4), 6-2 to reach the quarterfinals at a 35th consecutive Grand Slam tournament. The last time Federer failed to reach the last eight at a major was at the 2004 French Open, where he lost in the third round to Gustavo Kuerten. He next plays No. 7 Jo-Wilfried Tsonga, a finalist here in 2008. Raonic, seeded 13th, missed another chance to become the first Canadian man in a Grand Slam quarterfinal in the Open era.Murray cruisesU.S. Open champion Andy Murray advanced to the quarterfinals with a 6-3, 6-1, 6-3 win over Gilles Simon of France. The third-seeded Murray will play unseeded Frenchman Jeremy Chardy in the quarterfinals.