Venus Williams will play her sister Serena in the final of the Sony Ericsson Championships after the defending champion came from behind to beat Jelena Jankovic.

Venus lost the first set to the Serb and had break points against her in the second before hitting back to claim an impressive 5-7 6-3 6-4 victory.

"It's my last tournament of the year, so I'm trying to give a thousand per cent," said Venus.

"I wasn't feeling the ball very well in the first set, but I came back and had to make sure I played well against such a consistent player like Jelena."

Meanwhile, Serena Williams had surged into a 6-4 0-1 lead against Caroline Wozniacki in the other semi-final when the Dane was forced to retire with a stomach injury.

"She's been struggling throughout the entire tournament," admitted Serena. "She's just an incredible fighter to come out here today and put up an effort.

"I'm going to have to really improve my game against Venus if I want to win."