J.K. Rowling is a tennis fan. When the famed author of “Harry Potter” took to Twitter on Saturday to express her love for Serena Williams, many agreed with her.

Rowling tweeted:

#SerenaSlam! I love her. What an athlete, what a role model, what a woman!

#SerenaSlam! I love her. What an athlete, what a role model, what a woman!

— J.K. Rowling (@jk_rowling) July 11, 2015

While there were some on Twitter who were not quite as effusive in their praise of Serena Williams, there was a generally civil discussion of her merits.

@Seanchuckle @jk_rowling her work in Africa as well as many other charitable causes, as well as being a world class athlete would qualify

— James Lever (@James_D_Lever) July 11, 2015

But the headline-grabbing moment came when one user, based in the UK, challenged Rowling’s opinion of Williams.

@jk_rowling @hansmollman ironic then that main reason for her success is that she is built like a man

— Rob (@diegtristan8) July 11, 2015

Rowling’s retribution was swift.

.@diegtristan8 "she is built like a man". Yeah, my husband looks just like this in a dress. You're an idiot. pic.twitter.com/BCvT10MYkI

— J.K. Rowling (@jk_rowling) July 11, 2015

Fans of J.K. Rowling and Serena Williams alike took to their own Twitter handles to excoriate the fellow.

shamed enough yet, @diegtristan8? time for you to stand down … or apologize. #SerenaSlam #SerenaWilliams

— Mike Maynard (@ManerdM) July 11, 2015

@diegtristan8 I thought the reason for her success was that she's damned good at tennis? @jk_rowling @hansmollman

— Karen (@CamaroWRX) July 11, 2015

In the hours since, the fellow has spat comebacks on his own Twitter account.

Twitter 2015 where people object to others actually having an opinion

— Rob (@diegtristan8) July 11, 2015

The logic in using an old picture not showing her muscles to disagree with the opinion that she is muscly is redundant

— Rob (@diegtristan8) July 11, 2015

The fellow, whose identity we will not go into digging up, may be enjoying his 15 minutes of reflected fame, or he may wish he had kept his mouth shut. One thing is for sure, it is tough to express oneself eloquently in a few characters and without much aforethought.

This little tempest in a teapot is happening in an atmosphere in which women are speaking out about the unfairness of being judged primarily on looks.

Amy Schumer recently remarked, “For women, we’re taught to eat less until we disappear. And trained to believe that if you don’t look like everyone else, then you’re unlovable. And men are not trained that way. Men can look like whatever and still date a supermodel.”

And Jane Fonda also observed, “The perception of men as they get older is vastly different from women. Men are seen as becoming elegant and more desirable, whereas women are seen as having lost their beauty and attractiveness. It’s as if we become devalued because only our beauty defines us.”

Even if this fellow meant something other than was received by most observers, it’s a bad time to throw thoughtless comments. Women have put up with thoughtless comments and outright discrimination for too long.