EASTBOURNE, England - For two and a half years, the summit of the WTA's ace leaderboard has been Karolina Pliskova's domain. In 2015, she topped it with 517 aces; last year, she extended her total to 530 - the highest numbers of any woman this decade. Naturally, coming into the Aegon International in Eastbourne this week, the Czech was out in front for 2017, having delivered 249 aces in 39 matches.
The first three days in Eastbourne have seen the World No.3's position assailed, though - by none other than her twin sister, Kristyna. The World No.44 leapfrogged her younger-by-two-minutes sibling with her first-round victory over Naomi Broady, during which she hammered down 10 aces. Karolina could manage only seven en route to beating Alison Riske yesterday - which means that she now trails her left-handed twin by one with 256 to Kristyna's 257.
Talking to reporters afterwards, Karolina was sanguine about being overtaken. "Since it's in the family, I don't mind," she smiled. "But I'm sure she's gonna know it and she's gonna tell me!"
In part, Kristyna's increase in raw numbers can be attributed to her rise in the rankings. She spent the first half of 2016 largely outside the Top 100, and played just 13 WTA matches between January and June of that year. By contrast, she has competed in 30 WTA main draw matches to date in 2017.
Conversely, Karolina's own rise in the past 12 months from floating around the Top 20 to embedding herself in the Top 5 has also altered her schedule - by decreasing it. Take last year's grass season as an example: Karolina played every possible week, racking up a title in Nottingham and reaching the Eastbourne final. This year, with more of an eye on preserving herself for Wimbledon, Eastbourne is her first tournament on the surface. It should also be noted that Karolina has also played higher-quality opposition in 2017, with an average ranking of 45.9 versus Kristyna's 67 - and so the likelihood of the higher-ranked twin facing superior returners has gone up.
Dig deeper, though, and it's apparent that Kristyna's greater likelihood of hitting an ace isn't new. This year, she's racked up her superior total in fewer matches, averaging at 8.57 aces per match to Karolina's 6.4 - a statistic in which she led the whole WTA tour last year with 11.42 aces per match. (Karolina trailed her in second place with 8.69 aces per match.)
The serve has always been the bedrock of both Pliskovas' games: it's a stroke that Karolina described as "absolutely natural" after beating Garbiñe Muguruza at the BNP Paribas Open in Indian Wells this year. Contrary to the stereotype that service efficacy is all about strength, she continued: "I don't even use any power... It's just a swing, you know. I think 186 [kilometres per hour] is my fastest serve, which is not that much, you know. So there are girls which can hit 200 or more than 190." Nonetheless, the twins are are over 20 aces ahead of the No.3 player on the leaderboard, Lucie Safarova.
Which of the Pliskovas will take final honors?
With thanks to SAP Tennis Analytics for data and statistics.