Up at the net, most players are blank canvases, cradling a racket and generally standing still during the formality. Not Williams. She whips her arm in a service motion over and over, her racket slicing the air in a display akin to shadowboxing during a referee's instructions in a ring.
Bringing that intimidation to every shot on every surface against every opponent (including, finally, her older sister) in 2002, Williams was simply dominant, winning three of the four Grand Slam titles.
On Friday, Williams was honored as The Associated Press Female Athlete of the Year in a vote that was about as close as many of her matches.
She received 53 first-place votes and 351 points from writers and broadcasters across the country. Golfer Annika Sorenstam was next, with 27 first-place votes and 193 points, followed by Olympic champion figure skater Sarah Hughes (12 first-place votes, 158 points).
"I can't become satisfied, because if I get satisfied, I'll be like, 'Oh, I've won Wimbledon, I've won the U.S. Open. Now can I relax,"' Williams said. "But now people are really going to be fighting to beat me."
It didn't do a lot of good to try to beat her this year.
Williams won 56 of 61 matches (a .918 winning percentage), claimed a WTA Tour-leading eight titles (out of only 13 tournaments played), and took home a record $3.6 million. She was a runner-up twice and never fared worse than the quarterfinals.
She went 21-0 on her sport's biggest stages, beating sister Venus - who was fifth in the AP balloting after finishing second twice in a row - in the finals of the French Open on clay, Wimbledon on grass, and the U.S. Open on hard courts.
She didn't lose a set at the All England Club or Flushing Meadows en route to becoming just the sixth woman to win tennis' final three majors in a year (she dubbed it a "Serena Slam"). It might have been a Grand Slam sweep, but an ankle injury forced her to skip the Australian Open.
Williams had a season-best 21-match overall winning streak and took over the No. 1 ranking in July. Perhaps most striking was her complete turnaround against two of the best in the sport and her predecessors atop the rankings: Jennifer Capriati and Venus Williams. Serena went 0-4 against that pair in 2001, 9-0 against them in 2002.
"The difference is I'm a bit more mature, and I'm more relaxed," Serena said. "I'm a better player, obviously. But I just have more fun with what I do. I'm not as stressed out there as I used to be."
Her game features impressive power (her 53 aces during the U.S. Open were more than twice as many as any other woman) and all-court coverage, along with an ever-improving ability to construct points.
Not everything went according to plan for Williams this year.
Her parents completed their divorce, and she had to deal with a stalker who followed her around the world, getting arrested during Wimbledon and the U.S. Open. But the 21-year-old Williams never let anything off the court distract her on it.
"I'm a strong person," she said. "I try not to let things like that affect me."
Her burgeoning fame helped land new endorsements (including a McDonald's commercial featuring her and Venus) and TV appearances (on "The Oprah Winfrey Show" with Venus, a role as a kindergarten teacher on "My Wife and Kids").
And then there were her tennis outfits, including a green-and-yellow getup with knee-high socks at the French Open, and a snug black cat suit at the U.S. Open.
Shy? Ask her.
"I'm really exciting," Williams said. "I smile a lot, I win a lot, and I'm really sexy."
Others agree. She and Tiger Woods were deemed the most attractive spokespersons among athletes, according to a survey of the public relations industry.
"I think Serena likes the attention," said Venus, who's 15 months older. "Everyone has their year, and this is her year, and next year could be her year, also - I don't know. But I'm glad she's done well."
By Howard Fendrich