By HANNAH KARP

Tennis is rich with rivalries, but this year there’s a more unusual feud brewing on the courts: player versus commentator.

With the Tennis Channel and ESPN only covering the U.S. Open for the second year, the number of talking heads has mushroomed at the Grand Slams lately, and they’re not announcing matches in the hushed, respectful whispers still favored by British tennis fans and golf enthusiasts.

In order to appeal to the nontennis crowd, many are taking a chattier, more irreverent and in some cases just plain louder approach, and their commentary is zooming back to the players at lightening speed, thanks to text messaging and social-networking tools like Facebook and Twitter. The chatter is rankling some of the tour’s more sensitive players, like Maria Sharapova and Andy Roddick, not to mention purist fans accustomed to watching points in silence.

Mr. Roddick has been telling Tennis Channel commentator Justin Gimelstob in the locker room to “stop hammering his forehand,” and this week he sent him this text while watching a recording of Mr. Gimelstob announce one of his matches from his home in Brooklyn: “I’m enjoying watching you sweat all over yourself.”

The tension came to a head earlier this summer when James Blake heard ESPN commentator and former pro Pam Shriver criticizing his play from the sidelines at Wimbledon as he lost a match to Dutchman Robin Haase.

“Amazing you used to play tennis,” Mr. Blake yelled to Ms. Shriver. “I can still hear you.”

Ms. Shriver responded on the air: “He’s got rabbit ears,” trying to get him to concentrate, and obscenities ensued. Ms. Shriver says she shouldn’t have responded but was just trying to help.

“It was a little embarrassing—but you feel invested,” says Ms. Shriver, who was broadcasting from a new location for the first time and didn’t think her voice could be heard on the court. “I was emotional on the court, too, and I know it costs matches.”

(Ms. Shriver says she also butted heads with Mardy Fish earlier in his career because she was frustrated that he was not playing to his potential; she says as a generality, “male players have a harder time taking criticism from a female voice.”)

Mr. Blake, whose camp is also known for speaking up when they disagree with on-air comments, says he realizes she was just trying to do her job.

Many players shrug it off, of course, but some are more touchy than others, especially when they’re struggling. Ms. Sharapova recently became so sick of the relentless criticism and dissection of her serve on the air that Ms. Sharapova’s coach, Michael Joyce, begged the ESPN crew to lay off.

“He said, you’re just killing her serve,’” recalls Mary Carillo, a former player and ESPN announcer, adding that they did not adjust their commentary. (An agent for Ms. Sharapova declined to comment.) “You really can’t guard too much what you say—you have to call it like it is.”

Harsh commentators abound in all sports, of course, but in tennis, the individual nature makes it hard not to take things personally. And many top-ranked players get less and less accustomed to taking criticism as they rise through the ranks because their coaches and trainers are afraid of loosing their jobs.

“Many players don’t hear anything they don’t want to hear because the camp’s happiness depends on the player’s happiness,” says commentator Chris Fowler, adding that the dynamic is magnified on the men’s tour because the player is usually the “alpha-male” of his coaching entourage.

Mr. Fowler says he gets emotionally invested in the success of American players, and that he offended one top player recently with a comment that he was “in denial” about the state of his career. The player promptly informed him in an interview afterwards: “By the way, I am not in denial about anything.”

“He didn’t think it was funny at all,” says Mr. Fowler.

The tension spans the globe. Radek Stepanek says Czech commentators are so offensive that many of his friends watch him play with their TVs on mute.

Of course, not all the on-air comments that get back to players are hard to hear. John Isner says he’ll never forget hearing after his U.S. Open match in 2007 that Mr. McEnroe had proclaimed him to be a future top-20 player.

“Nobody knew who I was at the time, but he was right,” says Mr. Isner.

Write to Hannah Karp at hannah.karp@dowjones.com