Sony Ericsson Open, Miami
25 March to 5 April
Updates on BBC Radio 5 Live, live scores/text commentaries on BBC Sport website & mobiles. Live on Sky Sports.
Serena Williams is bidding for a record sixth Sony Ericsson Open title
Serena Williams remained the number one player in the world after beating sister Venus to progress through to the final of the Sony Ericsson Open.
The match was the 20th meeting between the pair and Serena's 6-4 3-6 6-3 win makes it 10 victories apiece.
She will meet Victoria Azarenka in Saturday's final after the Belarusian beat Svetlana Kuznetsova 6-3 2-6 7-5.
"I'm excited," said Serena. "I was thinking I'd love to stay number one. I was more happy with that than winning."
Serena needed to reach the final to retain the top ranking she has held since 2 February.
Had she lost, the American would have been replaced next week by number two-ranked Dinara Safina of Russia.
After a tight first two sets, Serena went 4-1 up in the third against her older sister before a decisive sixth break of the match helped her close out the win.
"Even though she's my sister, I'm still here to win," said Venus.
"I can't give anyone anything. So I'm disappointed that I lost, whether she kept the ranking or not."
Azarenka reached the final after a closely fought win over her Russian opponent in a match that lasted two hours and 40 minutes.
The world number 10 has never reached a top-tier final before, but she has had a good start to 2009 reaching the Indian Wells semi-finals two weeks ago.
Azarenka secured victory after Kuznetsova had saved three match points.
"All the work I have been doing is paying off," said Azarenka. "I was just trying to play every point from the beginning to the end.
"The second set didn't go so well for me, but I was still hanging in there and just played every point no matter what."