Serena Williams has just three opponents standing between her and a history-making Grand Slam win at the U.S. Open, but it likely won’t be easy. With the second and fifth seeds still in the tournament, Williams may have to face either Simona Halep or Petra Kvitova to sweep all four Grand Slams in 2015, but first she’ll have to face her big sister Venus in the quarterfinals on Tuesday night. How do they match up? Let’s look at the numbers.

Age:

Serena: 33

Venus: 35

It may seem like Serena has the advantage by two years, but if there’s anything both these sisters have taught us in the past few years, it’s that being older than your opponents isn’t necessarily a disadvantage. After all, every player both Serena and Venus has played so far in this U.S. Open has been younger than them.

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Matches won against each other:

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Serena: 15

Venus: 11

From this standpoint, Serena is looking good going into Tuesday night’s quarterfinal match. Not only is her record playing against her sister better overall, but she also already beat Venus at a Grand Slam this year. The two met in the fourth round of Wimbledon in July and Serena won in straight sets, 6-4, 6-3.

Matches won against each other in Grand Slams:

Serena: 8

Venus: 5

Serena’s stats may look dominant here, but things tip in Venus’s favor if you parse out just the early rounds of Grand Slams. Not counting semifinal or final matches, Venus actually has the winning record, with five wins compared to Serena’s three in quarterfinal or earlier matches. So you never know. Plus, looking at just this year’s U.S. Open, Venus’s serve has been on fire — even by Serena standards. Venus has 33 aces compared to Serena’s 26.

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Grand Slam wins: 

Serena: 21

Venus: 7

There’s no way Venus will ever surpass her sister’s Grand Slam tally at this point, but surely gaining on her by one has got to be enticing. Venus, however, tends to fare better on grass and the U.S. Open is a hard court tournament. Five of Venus’s titles came at Wimbledon; just two came at the U.S. Open.

Serena, meanwhile, has equal success in hard- and grass-court Grand Slam tournaments. She’s won both Wimbledon and the U.S. Open six times each. Additionally, she’s taken home the top prize on the hard courts of the Australian Open six times; she’s won the French Open, which takes place on clay, three times.

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Overall, Serena’s career at the U.S. Open far surpasses her sister’s. Serena is 83-9; Venus is 69-14.

2015 Record: 

Serena: 52-2

Venus: 28-10

There’s a reason Serena’s the No. 1 seed and Venus the 23rd. Serena hasn’t just played more matches in 2015, but she’s won more and lost fewer, which bodes well for her coming into Tuesday’s match against Venus. Of course, one reason for Serena’s prolificness could be that her interests aren’t quite as diversified as her sister’s. Venus not only runs an interior design business, but took the time to get her a business degree this year. Serena, meanwhile, hung out with Kim Kardashian, so that’s something…

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Career Record

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Serena: 736-122

Venus: 698-190

Both sisters have winning career records, but the odds in Vegas are on Serena. Her moneyline is currently set at -1000 compared to Venus’s, which is at +650, according to Bovada. This means to win $100 on Serena, you’d have to shell out a $1,000, while a $100 bet on Venus would earn you a $650 pot. Those are the most uneven odds in all of Tuesday’s quarterfinal tournaments.

The last time Venus beat Serena in a Grand Slam was in 2008, when the two squared off in the Wimbledon final. The odds were a lot more even back then. Even the gap has widened between the two sisters, however, Serena knows she shouldn’t doubt her sister.

“She’s a player that knows how to win, knows how to beat me and knows my weaknesses better than anyone,” Serena said this week (via USA Today).

She added: “I would rather lose to Venus as opposed to anyone else,” but, “I, in general, don’t like to lose.”

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