NEW YORK  Is the ball speed on Arthur Ashe Stadium faster than Wimbledon 's grass, traditionally considered the slickest of all surfaces?

Roger Federer says it is. Rafael Nadal and Andy Murray say it isn't. Svetlana Kuznetsova? She says the U.S. Open's Grandstand Court is quickest of all.

At least they can agree on this: The hardcourts at the U.S. Open stand apart for pace when compared to most hardcourts on both tours.

Opened in 1997, Ashe Stadium is by far the biggest and most cavernous of the four main Grand Slam stadiums. It has 23,771 seats and soars at its highest point to 190 feet.

By comparison, Wimbledon's Centre Court, renovated and expanded in 2009, seats 15,000.

Federer, who is seeking his seventh consecutive final, says grass is fast. But taking into account other factors — including temperature, ball type and time of day — Federer says the DecoTurf II cement at Flushing Meadows is zippier.

"I just feel on average the U.S. Open could be the fastest Grand Slam," said Federer, whose owns five U.S. Open titles among his record 16 Grand Slam triumphs. "You can really hit through the court if you play aggressive here."

It could also explain why his main rival, top-seeded Rafael Nadal, has not played well enough to go past the semifinals in seven tries.

"That could be one of the problems for Rafa here in the past," the No. 2 seed from Switzerland said. "But the problems are on a very high level. I mean, the guy's won in Australia; he's been here in (two) semis already; this guy doesn't need to learn how to play on hardcourts anymore."

Nadal disagrees. Asked if grass is faster than DecoTurf II, the No. 1 Spaniard said: "For sure. No question about that."

Fourth-seeded Andy Murray backed him up.

"I think Wimbledon is faster," the 2008 U.S. Open finalist said. "The balls are slower at Wimbledon, but the court itself is definitely quicker. Obviously the heat here can make the court fast, as well."

According to 1999 U.S. Open runner-up Todd Martin, it depends on the spin of the ball. "If the ball has slice on it, I believe that (Wimbledon) is still faster, but when the ball is hit with topspin Ashe might very well be quicker," Martin said.

Some players say Ashe plays faster than the outside courts, but U.S. Open officials beg to differ.

If anything, the three stadium courts — Ashe, Louis Armstrong and the Grandstand, which 2004 U.S. Open titlest Kuznetsova cites as quicker than Ashe — are slower than the other 31 outdoor courts on the grounds.

That's because they are surfaced later in the summer than the outside courts and therefore have less wear-and-tear from play, sun and rain.

"From a scientific perspective, it's virtually impossible for them to play faster," says Danny Zausner, managing director of the Billie Jean King National Tennis Center.

Hardcourt speed can be adjusted depending on the level of sand content in the layers of paint in the surface coating. But no "noticeable" changes to the surface composition in recent years have taken place, according to Zausner.

All of this sounds right to Pam Shriver, the former pro and ESPN commentator.

"I've always thought players had different opinions on what makes the speed of a court," says Shriver, who reached the 1978 U.S. Open final as a 16-year-old but never played on Ashe. "It can depend on who you are playing and what time of day or night it is. It's just your own personal opinion on what makes fast."

She also says it's not uncommon for courts within the same venue to have nuanced differences — perceived or real.

"I always reckon that it's like a cookie batch," she says. "You follow the directions just so but there is something different about some batches than others."

There is little controversy about the wind in Ashe. It's brutal. "It's kind of swirling," Jelena Jankovic said Tuesday after escaping 6-4, 4-6, 7-5 vs. teenager Simona Halep of Romania.

Adds Andy Roddick: "The stadium court is always tricky because that wind always gets down there and you're always playing downhill on one side, and it feels like uphill on another side. … So it's kind of almost like two different matches depending on what side you're on."