NEW YORK -- Roger Federer called this "the slowest US Open we've seen in years.''

Turns out that was no accident.

US Open tournament director David Brewer said Wednesday night that the Grand Slam event's hard courts were purposely slowed down "a touch'' in response to players noting in recent years that the surface seemed to be speeding up.

Rafael Nadal returns a shot during the US Open at Flushing Meadows, where the courts are slower this year. AP Photo/Carolyn Kaster

"In the general feedback we've gotten from players the last couple of years, a range of players, both male and female, the commonality we seemed to have been getting was: The courts were sort of gradually creeping up in speed,'' Brewer said in an interview. "We just felt we needed to address that a little bit this year. At the same time, we wanted to ensure we had really good consistency across all courts.''

The amount of sand or other granular items in the surface's top layer can be adjusted to make a court faster, which is what's responsible for the change, according to Brewer, rather than the recent switch from asphalt to cement underneath each court at Flushing Meadows.

Brewer also dismissed a theory raised by Jim Courier, an American former player who is serving as a commentator for Amazon TV during the US Open.

Courier said on Wednesday's telecast that officials believed American players would be more successful at the US Open if they slowed down the pace of the courts, so the surface was altered. Courier's notion was discounted by several tennis commentators, who noted that the best American men, including John Isner and Sam Querrey, prefer quick courts and that four American women made the US Open finals last year.

Brewer said he can't remember any concerted effort to alter court speeds with the intention of helping American players do well in the country's Grand Slam tournament.

"I'm just trying to think if we've ever sat down and said, 'All right, look, what can we do to advantage American players when it comes to the court surface?' And I don't ever recall having that conversation in my 20 years here,'' Brewer said.

No American man has won the singles title in New York since Andy Roddick in 2003, and none has even reached the semifinals since Roddick in 2006. The highest-seeded American man, Isner at No. 11, lost in the quarterfinals this week.

However, last year, all four US Open women's semifinalists were Americans, including champion Sloane Stephens. Two of the four women who play in Thursday's semifinals are from the United States -- Serena Williams and Madison Keys.

The Associated Press contributed to this report.