Serena Williams' serve has been widely acknowledged as the most dangerous weapon in the history of women's tennis.
Perhaps we should be talking about her mind.
At the age of 32, she is proving the old Clairol hair-coloring slogan to be true: She's not getting older; she's actually getting better.
This defies the career arc of virtually every previous tennis professional who has come before her.
"I don't know," she told reporters after advancing to the fourth round with a 6-3, 6-3 victory over No. 31 seed Daniela Hantuchova. "I feel like, you know, in life, 32 is young. In sports, it's old.
"But for whatever reason, I feel like I just never was really able to reach my full potential. And I feel like recently I just have been able to do a little better. I just keep trying to improve on everything."
On Sunday, she'll play No. 14 seed Ana Ivanovic in a match of two former Grand Slam singles winners that will vault the winner into the quarterfinals.
How have past champions done when they creep into 30-something territory? Not particularly well, especially relative to their glory days.
The obvious comparison is Roger Federer, who is also 32 and also owns 17 Grand Slam singles titles. Since turning 30 after the 2011 Wimbledon tournament, Federer has played 10 majors, winning only one, Wimbledon in 2012. Since turning 30 near the end of the 2011 season, Williams has won four of eight Grand Slams.
The great Steffi Graf played one Grand Slam after her 30th birthday, in 1999 at Wimbledon. She lost in a straight-sets final to Lindsay Davenport and promptly retired. Chris Evert played 16 majors after hitting 30 -- and won two, the French Open in 1985 and 1986. Martina Navratilova played 23 majors and won three Grand Slam singles titles, but two of those came in her 31st year. Margaret Court, who leads all women with 24 major championships, played eight past 30 and won three, all of them coming in her 31st year.
And then there's this: After their 32nd birthdays, Evert, Navratilova and Court won a combined total of only one major -- Navratilova's title at Wimbledon in 1990 at 33. The way Williams is playing, it wouldn't be terribly surprising if she won two or three this year.
Even when she's missing, you can see the wheels turning in her head. Against Hantuchova, she had a string of five consecutive unforced errors in the first three games.
"I was just trying to get my bearings, trying to figure out [how] to do the right thing," she said. "I wasn't fully on today, so I was just trying to see if I could just go for it and how far out they were going to be, trying to make them."
Like an expert marksman dialing in on a target, she soon got the calibration right -- and annihilated Hantuchova, who later opined on Facebook that Serena is the best women's player ever. Is the same punishment in store for Ivanovic? History says … yes.
The two have met four times -- three, curiously, at the US Open -- and Williams has never lost a set. Ivanovic has never gotten more than four games in a frame.