NEW YORK -- When the video of Sabine Lisicki breaking the WTA Tour's record for the fastest serve began making the rounds on the Internet almost immediately after she struck it four weeks ago, the wonderment seemed split regarding what was more impressive.
Was it that Lisicki, whose tour nickname is "Boom Boom," reached back on game point and smoked the ball at 131 mph -- the same neighborhood as the great Roger Federer and Rafael Nadal typically serve? Or that Ana Ivanovic, her opponent that day at the Bank of the West Classic in Stanford, California, actually managed to get her racket around to smack a clean return that, alas, landed wide?
"It's about time it was broken," said Venus Williams, who had owned the previous record of 129 mph since 2007. "It's a good thing."
The evolution of big servers in the women's game is an interesting subject at this year's US Open, in particular, because of the way the speeds just keep climbing up, up, up to unforeseen levels previously considered supersonic for men. And because top-ranked Serena Williams has ridden that most formidable part of her game to the point that she will have tied Chris Evert and Martina Navratilova's career total of 18 Grand Slams -- the fourth-best total of all time -- if she wins this tournament.
Serena's serve is generally considered the greatest the women's game has ever seen, and Venus' serve isn't far behind.
Lisicki, a 24-year-old German who defeated Serena at Wimbledon last year just as Serena was having one of the best seasons of her career on the way to 11 titles, is among the few players who can routinely match both Williamses' power. But the group is steadily expanding.
According to a list compiled by the WTA, the 10 fastest serves of all time in the women's game have all happened in the past seven years., which raises some natural questions about why. And what does it mean for the game?
Right about here, it's important to emphasize, as Venus did during the same tournament Lisicki broke her record, that there's a big difference between a player with a fast serve and a player with a great service hold game.
The latter kind of player -- someone who knows how to vary her serve by changing the pace and location and angles and get in a high percentage of first serves -- can be just as effective, or even win more than a player who is merely able to reach back for a couple more miles per hour.
And a look at the top-10 fastest servers versus the current top 10 rankings confirms this: Only Serena and Ivanovic appear on both lists.
As 34-year-old Venus says, "I'm not out there trying to serve hard. I used to, but now when I really want the point, I try a medium serve somewhere above 110. I try for more placement these days. It takes a lot of energy to serve, so if you can take 10 miles off and place it, it's smarter."
There's been a lot of conjecture about why serve speeds are climbing to incredible heights in the women's game. (The trend is the same in the men's game, too, by the way. Andy Roddick's old record of 149 was blown away by Samuel Groth's best of 163.7 mph at a 2012 Challenger tournament in South Korea.)
But unlike, say, the unending mystery in baseball about when and why home runs come, the answers about climbing service speeds aren't as elusive as you might think.
There are people who study this stuff all the time -- sometimes to mind-bending degrees of using specially designed algorithms and deep-dive statistical looks at an entire year, or even decades, on the tour. Some of them insist two of the most oft-cited reasons for speed changes -- modern racket technology and the tweaking of playing surfaces on the tour -- are demonstrably not the explanations, regardless of how much those two reasons get repeated.
Jeff Sackmann, who writes the tennis blog HeavyTopspin.com, did a remarkably detailed statistical analysis on court surface speeds last year. His takeaway was basically, "It's not the courts, stupid." As he wrote: "However fast or high balls are bouncing off of today's tennis surfaces, courts just aren't playing any less diversely than they used to. ... It's time for pundits to find something else to complain about. ... If surfaces are converging, why is there a bigger difference in aces now than there was 10, 15, or 20 years ago? Why don't we see hard-court break rates getting any closer to clay-court [service] break rates?"
Ron Rocchi, a senior designer and the global tour manager for Wilson, the company that is handling the stringing of player rackets at the US Open, indirectly supplies the answer: He thinks it's the players who have improved and changed most.
"In my opinion, if there is any part of the racket technology that's contributing to [increased service speeds in the women's game], it's a very small part, because, essentially, in the last 5-7 years, the rackets that are being used haven't changed all that much," Rocchi said Wednesday at the Open, speaking in the racket stringing room that sits not far from the players locker rooms inside Arthur Ashe Stadium.
"The rackets are relatively the same length, same head size, same stiffness and, in most cases, the same string. So, to me, one of the major attributes to how speeds have changed -- certainly among all special tennis players, but especially on the women's side -- is you have a much more emphasis put on training to become the best possible physical specimen you can get to, along with having really better technique. And those two factors are contributing to higher ball speeds more than a racket change has. It's how fast you swing the racket."
Rocchi says if a player wants to, she could certainly reduce the tension on her strings to get a bit more power.
"But remember," Rocchi said with a smile, "after you hit that bigger serve, you have to start playing other shots. So you will lose some control in most cases with a lower tension. It's a balance. And though speeds on the women's tour are rising, I have not seen that trend of, OK, all the women are going to a [different] racket to get more speed, either. Relatively speaking, the racket and the specs have, for the most part, remained the same, too. As a group, nothing has dramatically changed that would lead to this, or saying, 'Hey, the ball is now jumping up in miles per hour.' "
And so? Rocchi smiles now and repeats, "In my opinion, it's not coming from the racket."
Lisicki -- like Venus and Serena -- says the same thing. Asked before the Open began how she came up with such terrific power, Lisicki said, "I've worked very hard on my serve from a young age, and I consider my serve a weapon. It's great to be recognized for my hard work."
But even she admits she still has some work to do. While it's true Serena and Lisicki might often bully players right off the court -- see the second set of Serena's match Tuesday night against 18-year-old Taylor Townsend -- there are no guarantees.
Despite touching 120 or more on the radar gun Wednesday against American wild-card entry Madison Brengle, Lisicki had to scramble back from having her service broken in the match's opening game before prevailing 6-4, 6-1.
Even the day she thumped that record serve in Stanford, she ended up losing to Ivanovic. The fact that most women train with male hitting partners today means even if they're not top-shelf servers themselves, they're well practiced at returning serves hit to them at high speed. Ivanovic, the No. 9 player in the world, had this going for her, too: She used to be Lisicki's doubles partner.
Some days even the best "Boom Boom" tennis players go boom themselves.