– Venus Williams summed it up short and sweet.

"Getting to a Grand Slam semifinal is the next step toward the final," she said. "We all know what's at stake here."

What's at stake Tuesday when Venus plays sister Serena in a U.S. Open quarterfinal? Serena, at 33, is an Open title away from completing a calendar year Grand Slam. Venus, at 35, is more than halfway to a title she last won in 2001.

The match was set up when the sisters, playing back-to-back at Ashe Stadium on Sunday in fourth-round matches, steamrolled through their opponents, spending less than a total of two hours on court. First Venus defeated Estonian qualifier Anett Kontaveit, 6-2, 6-1, in 50 minutes, then Serena beat promising American Madison Keys, 6-3, 6-3, in 1 hour, 8 minutes.

The sisters haven't played each other at the Open since a scintillating quarterfinal match in 2008 that Serena won in two tiebreak sets. They have played each other a total of four times at the Open and each has two wins.

Neither Kontaveit nor Keys thought the sisters had given them any breathing room and left them gasping for air.

"She was playing really, really well today," Keys said of Serena. "I feel like I had to play my absolute best. It was one of those things where if I wasn't hitting a winner, I feel like she was. She wasn't giving me many unforced errors."

New York Times