KEY BISCAYNE – Serena Williams stayed on track to win her fifth Sony Ericsson Open title with a 3-6, 7-5, 6-3 win over Russia’s Svetlana Kuznetsova on Thursday.

Kuznetsova won four straight games, taking command of the first set.
She was closing in on a 5-5 victory in the second.

But after taking an injury timeout to receive treatment for a back injury, Williams recovered to reach her sixth final at the event, avenging a Kuznetsova victory over sister Venus in the quarterfinals.

In this Saturday’s final, the No. 8- seeded Williams is scheduled to play the winner of the semifinal Thursday night between No. 4 Jelena Jankovic and No. 19 Vera Zvonareva.

As the Open’s defending 2007 champion, little sister Serena has stolen the show this year.

She started out winning convincingly 6-1, 6-2 over an over-matched Edina Gallovits, barely breaking a sweat. It was the first match-up between the two and the first main draw for Gallovits.

Serena then went on to beat out a slightly tougher Flavia Pennetta of Italy 6-7, 6-3, and 6-2. Fourth round action saw her dismantle Kaia Kanepi of the Republic of Estonia 6-3, 6-3.

Next, in quarterfinal action, Serena was supposed to be facing her toughest opponent in Belgium’s Justine Henin. Henin came into the tournament as the one to beat, as the current top-ranked women’s player.

Both were 6-6 all-time against one another heading into this year’s Open match.

But on April 1, Henin proved to be no match for Serena, who blew her out in a short and sweet 6-2, 6-0 final that took only 80 minutes.

“There is no question we definitely bring out some of the best tennis in each other,’’ Williams said.

Her sister, Venus Williams, the defending 2007 Wimbledon champion, did not fare as well in the Sony Ericsson Open, losing to Kuznetsova in the quarterfinal.

Early in the tournament, Venus came in as the world’s seventh-ranked player and a six-seed in the tourney, digging in quickly and making short work of Poland’s Marta Domachowska.

The 22-year old Domachowska made just her third main draw appearance to Venus Williams’ tenth. That experience and familiar territory was enough for Venus, who won in two sets 6-4, 6-3.

With a 35-6 record through her first nine appearances in Miami, Venus was on an upward swing during the early matches.

“I feel very comfortable here (at the Open). I and Serena have done well here,” she said.

Then she moved on to take out New Zealand’s Marina Erakovic 6-2, 6-1 in round three, and 6-3, 6-3 over Denmark’s Caroline Wozniacki in fourth-round action.

But in the quarterfinals, third-seed Kuznetsova defeated Venus 6-4, 6-4.

Together, the Williams sisters have captured seven titles in the tourney dating back to 1998 in what is now the largest annually sponsored title tournament on the ATP tour.

The Associated Press contributed to this story.