Serena picked up the family’s first Grand Slam tournament title, surprising the tennis world, fittingly, at the 1999 U.S. Open. She also won her first two tour championships that year. She won in New York again in 2002, which was the year she was No. 1 in the rankings and captured eight other tournament trophies.

Venus earned her first title in New York in 2000 after winning her first Wimbledon championship. That season, she put together a 35-match win streak, the longest of the millennium, and also won both the Wimbledon and Olympic doubles with Serena. The next year, she again was victorious in London and New York, where she defeated Serena in the final.

They are 8-8 in career meetings, but Serena is ahead 6-5 in hard court contests. Venus won the first two encounters with her sister, the first in Australia 1998 and the second in Miami a year later. Serena also picked up a victory in 1999 at the Grand Slam Cup. In 2001, they traded wins. Serena got a walkover at Indian Well because Venus injured her knee. Venus evened the score for the year, defeating her sister 6-2, 6-4 in the U.S. Open final. Serena was a two-time hard court winner in 2002, including a 6-4, 6-3 U.S. Open victory. She did it again in the 2003 Australian Open final. Venus gained another win in Miami and in the round of 16 in New York 7-6, 6-2 in 2005. Their last meeting on the surface was in the Bangalore semifinals where Serena triumphed 6-3, 3-6, 7-6.

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In the poll we did on television, people think Venus is going to win. I think they feel this way because she is the Wimbledon champion. They don’t understand how tough it is to play someone you are so close to. They don’t understand how difficult it is and the emotions that are involved.

They are both playing well so it will not be like the match they played in 2005 when Serena hadn’t played much and wasn’t as consistent or prepared as she is now. Serena has trained hard throughout the year, and she is very hungry. Venus has already won a Grand Slam tournament this year, and Serena wants one, too. Because of everything involved, I can’t pick a winner. It’s 50-50.

I think it’s going to be a memorable match. They haven’t played each other here in six years and the way they have been competing, it holds promise to be one of the best ever Williams versus Williams contest.