( CNN ) -- Serena Williams is through to her ninth Miami Masters final after beating Maria Sharapova at Crandon Park on Thursday . Defending champion Williams trailed early on in the match before powering her way past her Russian opponent in straight sets 6-4 6-3 . Sharapova had worked an early lead , breaking in the fourth game of the opening set and led 4-1 at one stage . But her advantage was short-lived as Williams reeled off five games in a row to close out the set . The fourth seed broke Williams again in the second game of the second set to steal an early advantage , but any momentum gained was immediately lost as the world No . 1 broke back in the very next game . Further breaks in the seventh and finally the ninth game sealed Sharapova 's fate , dashing hopes that she could break her duck in a tournament where she has finished runner-up on five occasions . `` It was n't easy , '' Williams said afterwards . `` Obviously Maria plays really well , and she 's done really well here , so I just decided I had to do a little better , stay focused and make more shots . '' This latest defeat is the Russian 's 15th in a row against the American -- a sequence which stretches all the way back to 2004 . Williams will play Li Na in Saturday 's final after China 's world No . 2 beat Dominika Cibulkova in a rematch of January 's Australian Open title match . It went to three sets , as did their quarterfinal clash at Indian Wells this month , before Li prevailed 7-5 2-6 6-3 against the Slovakian 10th seed to become the first player from her country to reach the Miami final . The 32-year-old is seeking to end a run of nine consecutive defeats against Williams , the last of which was in the final of last season 's WTA Championships . `` It 's a good challenge , I think , '' she said . `` Here we can really see how I 've improved in these three , four months . '' World No . 1 Rafael Nadal fought his way into the men 's semifinals , where he will face 2010 runner-up Tomas Berdych . The Spaniard needed to come from behind against big-serving Canadian Milos Raonic , winning 4-6 6-2 6-4 in two hours and 35 minutes . `` For me to be in semifinals after losing early in Indian Wells is very important for my confidence , '' said Nadal , a three-time losing finalist in the hard-court tournament . Nadal has a 16-match winning streak against Berdych , who will return to the top five in the rankings after earlier battling past Ukraine 's Alexandr Dolgopolov 6-4 7-6 ( 7/3 ) in the third quarterfinal . It was the Czech 's 450th ATP Tour victory , making him just the ninth active player to achieve that milestone . `` He was a very tricky opponent , '' said Berdych . `` Even the conditions were not the perfect way that I really like . It was quite windy , so it was a little bit more difficult . But I handled it quite well . '' World No . 2 Novak Djokovic and Japan 's Kei Nishikori , who beat Andy Murray and Roger Federer respectively in their quarterfinal ties , will contest the first semifinal on Friday . Read more : Roger Federer upset by Kei Nishikori . Watch : Venus Williams fights incurable disease .
Serena Williams advances to Miami Masters final with straight sets semifinal win . Defending champion beats Maria Sharapova for 15th time in a row . American will next face Australian Open champion Li Na . Men 's No . 1 Rafael Nadal sets up semifinal clash with Tomas Berdych .