NEW YORK -- Serena Williams isn't the only Grand Slam champion using profanity at the U.S. Open: Roger Federer let an expletive fly, too.

In an uncharacteristic display, Federer argued with chair umpire Jake Garner during a changeover in the U.S. Open final Monday. He said his opponent, Juan Martin del Potro, was given too much time to challenge a line call.

"I wasn't allowed to challenge after 2 seconds. The guy takes, like, 10," Federer said.

Then the 15-time major champion used a profanity in addressing Garner: "Don't tell me to be quiet, OK? When I want to talk, I talk. I don't give a ... what he said."

CBS microphones picked up the exchange during its live broadcast of the match.

"It's regrettable, of course," CBS spokeswoman LeslieAnne Wade said. "But it's a part of the live coverage of sports events."