“I think I enjoyed like the first half of the basket, and then. . . like the other hundred balls that were left in there, I didn't like it so much.”—Madison Keys, following her second-round win at Wimbledon, on developing and practicing her serve.

Just 18 years old, Madison Keys is creating a sensation at Wimbledon, and not just because of her quality back-to-back wins over Heather Watson and Mona Barthel.

At 5’10”, Keys is already serving in the 120 M.P.H. vicinity, and backing it up so effectively that she’s holding with ease. Against Barthel, she faced just one measly break point, and swept that one aside.

It was a persuasive performance by one of the most precocious among the fleet of rapidly improving young American women, all of whom look to Serena Williams as the role model that one or more of them will be called upon to replace at some point in the next few years.

Keys is already the pride of Rock Island, Illinois, one of the famed (or not so well-known) among the “Quad Cities” that straddle the Mississippi River in either Iowa or Illinois. I guess someone in that part of the U.S. heartland wasn’t too good at math, because there are actually five towns that make up the “Quad Cities,” but why get all picky? The main thing is that Keys is moving up and out—as much as she loves her home town.

“I loved Rock Island,” she said after her win over Barthel on Thursday. “I still consider it home for me (despite having been a student in resident at the Chris Evert/USTA training facility in Boca Raton. Fla.). We have amazing ice cream. It’s probably the best part about it, but it's also a very small town. Everyone knows everyone.”

Keys knows about firepower in more ways than one. Rock City also happens to be home to the largest weapons manufacturing arsenal in the nation. Keys began to develop her own big weapon in the driveway of her family’s home, doggedly earning her way to court time in the only tennis club in the Quad Cities.

“When I first started serving, I had horrible technique,” she remembers. “It was just an awful grip. It was not very good. Kind of the pancake serve. I just had to work really hard on getting the right technique and the right grip and all that. I just hit lots and lots of serves.”

All that work paid off at a relatively young age for Keys. She was never ranked higher than a modest No. 35 in the juniors, but became one of the youngest players in WTA history to win a match in a tour event when she toppled Alla Kudryavtseva (then No. 81) in Ponte Vedra, Fla. Keys was 14 years and 48 days old at the time.

Despite having that first-strike weapon, Keys remains reluctant to attack the net behind the serve. She’s more Lindsay Davenport than Martina Navratilova, but that might change as her coordination catches up to her age, and her game takes on more tone and color. Right now, the big serve and forehand are the twin pillars of her game—although she’ll take the net behind a sufficiently aggressive groundstroke.

“I think about it,” she confessed, contemplating the allure of serve-and-volley tennis. “And then I get up to the line and I hit it. I'm like . . . ‘No, I'll stay at the baseline instead of going up to the net.’ I don't think I've ever served and volleyed in a singles match. Not once. (But) I really want to work on it more.”

It’s rare for a player to add new wrinkles to her game once she’s out of the junior ranks, but in some ways Keys is a late developer (despite the power that earned her some big wins at a young age, including one over her paragon Serena Williams—although that was in a World Team Tennis mini-match). And anyway, the classic, serve-and-volley attacking game has been in a significant, long-term retreat these past few years.

As much a product of her times as any player, Keys is more inclined to use the big serve to set up her forehand, which she also hits with gusto—even on Wimbledon grass, where the bounce can be unpredictable, and the grass has been particularly slick. It hasn’t bothered Keys much this week; in fact, she’s grown fond of the grass and prefers it to clay, although hard court remains her surface of choice.

“I just like how big serves and big forehands are rewarded (on grass),” she says. “I even feel like I can come to the net a little bit more comfortably than on other surfaces. It’s been a little bit slippery, but nothing out of the ordinary.”

Keys will have her work cut out in her next round, where she will face No. 4 seed and 2012 finalist Agnieszka Radwanska. The first and only time they’ve played (Miami, 2012) Radwanska allowed Keys just one game in each set. But don’t underestimate Keys; she’s is a fighter. While some of her young peers were ga-ga for the shopping on this trip to Europe, Keys was most impressed by a visit to the home of the gladiators, the Coliseum in Rome.

She didn’t say anything about the Italian gelato; I suppose the ice cream in Rock Island really is hard to beat.