Venus (left) and Serena Williams

Williams vs. Williams: Venus and Serena's Sibling Rivalry (Testing Update)

Signature moments from the sisters' head-to-head history.

With an astonishing 30 combined Grand Slam singles titles between them, the Williams sisters have reigned on the world's tennis courts for two decades. In that time, Venus and Serena, now 37 and 36 respectively, have faced one another 29 times, trading ground strokes and trophies in a sibling rivalry unmatched in its longevity and level of play. Serena holds a 17-12 advantage in the series. (Not incidentally, the sisters have also teamed up for 14 Grand Slam doubles titles.) Here, FOTO pays tribute to signature moments in their head-to-head history...

1998 Australian Open Second Round Gary M. Prior/Getty Images 1998 Australian Open Second Round Their rivalry made its debut Down Under in the second round of the 1998 Australian Open. The 17-year-old Venus beat her younger sister 7–6(4), 6–1, eventually losing in the quarter-final to Lindsay Davenport. A month later, they would team up for the first time as professionals, winning the IGA Tennis Classic for their first of 22 career doubles titles. 1999 Grand Slam Cup Final Clive Brunskill/Getty Images 1999 Grand Slam Cup Final Two weeks removed from becoming the first of the sisters to win a Grand Slam title (U.S. Open), Serena got her first win over Venus, in the finals of the Grand Slam Cup in Munich, Germany. 2000 Wimbledon Semi-Final Jon Buckle - EMPICS 2000 Wimbledon Semi-Final In the first of their six meetings at Wimbledon, Venus came out on top 6-2, 7-6(3) en route to her first career Grand Slam singles title. Days later the two teamed up to win their third Grand Slam doubles title. 2001 U.S. Open Final Simon Bruty/Sports Illustrated/Getty Images 2001 U.S. Open Final The climax of the 2001 U.S. Open marked the first major final contested between sisters in the Open Era. The Saturday night prime-time match-up saw Venus cruise to a 6-4, 6-3 victory to claim her second straight U.S. Open title. 2002 Nasdaq-100 Semi-Final Clive Brunskill/Getty Images 2002 Nasdaq-100 Semi-Final Venus came into the semi-finals of the 2002 Nasdaq-100 Open riding a 22-match win streak, but Serena was brilliant in Miami, cruising to a 6-2, 6-2 victory in just 49 minutes and the first of six straight head-to-head victories. 2002 French Open Final ANDRE DURAND/AFP/Getty Images 2002 French Open Final Facing off on the Roland Garros clay as the top two women's players in the world, Serena continued her winning ways, edging Venus 7-5, 6-3 to win the first of her three French Open singles titles. And the year was just heating up... 2002 Wimbledon Final Mike Egerton - EMPICS 2002 Wimbledon Final Serena continued where she left off at the French Open, downing Venus 7-6(4), 6-3 in the Wimbledon final. With the win — her first ever singles title at the All-England Club — Serena skipped over her sister in the rankings to claim the world No. 1. 2002 U.S. Open Final TIMOTHY A. CLARY/AFP/Getty Images 2002 U.S. Open Final A year after their first meeting in the finals at Flushing Meadow, the sisters put on a spectacular display, this time with Serena coming out on top 6-4, 6-3 to even the all-time series at five each. 2003 Australian Open Final Phil Walter - EMPICS 2003 Australian Open Final In one of their most tightly-contested Grand Slam finals in the head-to-head series — and their fourth in a row — Serena defeated Venus 7-6(4), 3-6, 6-4 to complete the so-called "Serena Slam" in which she became the first woman to simultaneously hold every major title since Steffi Graf in 1995. 2008 Wimbledon Final CARL DE SOUZA/AFP/Getty Images 2008 Wimbledon Final Meeting in a Grand Slam final for the first time since their show down at the All England Club in 2003, Venus came out on top 7-5, 6-4 for her fifth career Wimbledon title. 2008 U.S. Open Quarter-Final Jim McIsaac/Getty Images 2008 U.S. Open Quarter-Final Serena advanced to the semi-finals after edging Venus 7-6(6), 7-6(6) en route to her third career U.S. Open title. 2009 Wimbledon Final Clive Brunskill/Getty Images 2009 Wimbledon Final Meeting in their second consecutive Wimbledon final, Serena took the title — the 11th Grand Slam of her career — with a straight-set 7-6(3), 6-2 victory over Venus. The two would have to wait nine years before facing off in another Grand Slam final. 2014 Canadian Masters Semi-Final Icon Sports Wire/Corbis via Getty Images 2014 Canadian Masters Semi-Final After five years without a victory over her sister, 34-year-old Venus came back from three injury-plagued seasons to defeat Serena 6-7(2), 6-2, 6-3. 2015 U.S. Open Quarter-Final Al Bello/Getty Images 2015 U.S. Open Quarter-Final In perhaps their final face-off at the U.S. Open, the sisters slugged it out in three sets in front of a packed house in Flushing, with Serena coming out on top 6-2, 1-6, 6-3. 2017 Australian Open Final Scott Barbour/Getty Images 2017 Australian Open Final Serena's milestone 23rd Grand Slam singles title — the most by any player in the Open Era — came with a 6-4, 6-4 victory over Venus in their mind-boggling ninth head-to-head meeting in a major final.