There's a full day of tennis at the U.S. Open on Sept. 3rd, but most of the attention is focused on the intriguing matchups under the lights at Arthur Ashe Stadium.

At 7p.m. Serena Williams takes on big sister Venus Williams in the women's quarterfinals. Both sisters have been cruising with straight-set wins to this point. On Monday Venus crushed Polish player Agnieszka Radwanska in the daytime, while Serena manhandled Frenchwoman Severine Bremond at night.

After the clash of the Williams sisters comes a much-anticipated matchup in the men's quarters: world number-one Rafael Nadal vs. on-a-roll American player Mardy Fish. Fish upset his friend James Blake in straight sets a few days back, then defeated Frenchman Gael Monfils on Monday in four sets.

There are other attractive though less star-worthy quarterfinal matches in the day session: Flavia Pennetta vs. number-six seed Dinara Safina for the women, and Juan Martin Del Potro vs. rising Scottish player Andy Murray.

And for the nostalgia fans, two great women's players from the past are playing in the semis of the "Women's Singles Champions" draw: Martina Navratilova vs. Jana Novotna.