Serena Williams survived a scare from Chinas Li Na to advance to the semi-finals of the Miami tournament where she awaits a tussle against her sister. Top seed Serena Williams lost the first five games but rallied to beat Li 4-6 7-6 (1) 6-2 in the quarter-finals. She will face sister Venus,who earned a semi-final berth with a 6-1 6-4 win over Czech Iveta Benesova.
The other semi-final will be between eighth-seed Svetlana Kuznetsova and No 11 Victoria Azarenka.
Roger Federer defeated Andy Roddick 6-3 4-6 6-4 to set up a semi-final meeting with Serbian Novak Djokovic. Third seed Djokovic produced sparkling tennis to beat Frenchman Jo-Wilfried Tsonga 6-3 6-4.
Sania-Chuang in semi-finals
Continuing their dream run,Indias Sania Mirza and her Taiwanese partner Chuang Chia-Jung humbled second seeded Anabel Medina Garrigues and Virginia Ruano Pascual 6-3 7-6 (4) to sail into the womens doubles semi-finals.
On a day of upsets,Sania and Chuang made their presence felt against their seeded opponents,whose last ditch effort for a fightback wilted in the second set tie-break with the Indo-Taiwanese pair seeing it through.