NEW YORK -- Can Venus Williams halt her younger sister's march toward history?
That is the $64,000 question heading into the Williams Sisters' epic US Open quarterfinal match on Tuesday night in Arthur Ashe Stadium.
"I'm playing, for me, the best player in the tournament, and that's never easy," Serena, 33, said of her 27th career professional match against Venus, 35. "She's beaten me so many times. I've taken a lot of losses off of her - more than anybody.
"Yeah, she's a player that knows how to win, knows how to beat me, and knows my weaknesses better than anyone. So it's not an easy match at all. Hopefully things will go right."
Top-seeded Serena is seeking to become the first person since Steffi Graf in 1988 to win the calendar Grand Slam. She is now three matches shy of accomplishing that goal, with Venus standing between her and a spot in the semifinals.
Serena holds a 15-11 edge against her older sister and has won six of the last seven against Venus, the No. 23 seed.
On top of that, Serena has now won 25 straight US Open matches and 32 consecutive Grand Slam tournament matches. Serena is also seeking to tie Graf for second all-time by winning her 22nd career Grand Slam singles title.
Venus owns seven major titles, including the US Open in 2000 and 2001 but will enter as the underdog. Still, she is playing at a very high level despite having to battle Sjögren's syndrome, an autoimmune disease that caused her to withdraw from the 2011 US Open.
Venus beat the young Swiss star Belinda Bencic in straight sets in the third round -- a match many thought would be difficult -- and then easily dispatched Anett Kontaveit of Estonia in 50 minutes on Sunday.
The bottom line for Venus is, does she actually believe she can beat her younger sister, and will she have the intestinal fortitude to stand in the way of Serena's march toward history.
"For Venus to win it, she would have to serve so well and then she'd have to try to draw a bead on Serena's serve," Mary Carillo, an analyst for The Tennis Channel, told Metro. "I mean, to me the quality of Venus' second serve could determine the whole match. If she can keep her serving numbers up, so she doesn't have to throw down a lot of second serves, then she might be in decent shape. She's been playing beautifully and attacking the ball. She wants to get to the net more than her sister."
Emotionally it might be a whole other situation for Venus, but Carillo says she's up for it.
"How emotionally fraught is this match for both of them?" Carillo asked. "For Venus to beat Serena it would be the best win of her whole season. For Serena to beat Venus, it means that she would have to go through her own sister to get to history.
"Guess what, they both want to win this match. It's not like Venus is going to say, 'This is important to you.' And Serena would hate that. Serena wants to beat her, she doesn't want to be given it."
Venus says she's intent on winning, even if it means preventing the Grand Slam.
"I don't think anyone wants to be a spoiler," she said. "I think people love to see history being made. I think. No one is out to be a spoiler, but at the same time, you're focused on winning your match."
From her perspective, Serena says it's easier to play her sister at this stage of their careers than when they were younger.
From the 2002 French Open until the 2003 Wimbledon, the sisters met in the finals of five major tournaments, with Serena posting a 5-0 record against her sister.
Now Serena admits it's a little more fun than those earlier encounters.
"Nowadays, I would agree, I think it's more fun than it used to be," Serena said. "We really relish the opportunity. We're both happy to still be involved in getting so far. And it's still super intense. She's doing well and she wants to win this. So do I. It's not easy."
Serena added: "I would rather lose to Venus as opposed to anyone else. I, in general, don't like to lose."
Follow Adam Zagoria on Twitter @AdamZagoria for updates throughout the U.S. Open.