David Ferrer kept up his surprising run at the U.S. Open, reaching his first Grand Slam semifinal by defeating Juan Ignacio Chela 6-2, 6-3, 7-5 on a quiet day at Flushing Meadows today.

After running Rafael Nadal ragged earlier this week, Ferrer finished off Chela with a 100 mph ace down the middle on a second serve.

The 15th-seeded Spaniard is known for his great returns and he’ll be back to play the winner of the night match between no. 3 Novak Djokovic and no. 17 Carlos Moya.

“I prefer Carlos because he’s my friend and he’s a Spanish guy,” Ferrer said.

Ferrer is only 2-6 against Moya, as opposed to 2-1 vs. Djokovic. Still, Ferrer has played his countrymen better and better in recent years.

A day after Roger Federer, Andy Roddick, Venus Williams, and Jelena Jankovic thrilled the crowd with tiebreakers, it was far from a high-voltage afternoon at center court.

There was a constant murmur inside Arthur Ashe Stadium – many fans were chattering during play, and no one bothered to hush them. A few cell phones went off, usually a clear no-no met with stern looks.

Midway through the Ferrer-Chela match, the concession stands that sell $6 Coney Island hot dogs were empty. So were the counters were they line up Grey Goose vodka bottles for $8 mixed drinks.

Hardly anyone walked into to the Ralph Lauren walk-in boutique store on the suite level, either.

The 20th-ranked Chela had won the previous meetings against Ferrer, both in 2004. Like Ferrer, the Argentine was trying to make it to his first Slam semi.

Coming off a pair of five-set matches, Chela tried to rally in the second set. The eighth game went to seven deuces before Chela won, then Ferrer came back and quickly closed it out.

Last night, facing Federer, Roddick was very good, quite possibly as good as he can be.

For two sets, Roddick banged big serves at up to 146 mph, collecting aces and service winners, and never double-faulting, never facing a break point.

For two sets, he conjured up groundstroke winners, strong volleys, impressive returns.

And what did all of that superb play earn Roddick? A two-set deficit and, eventually, a 7-6 (5), 7-6 (4), 6-2 loss in the U.S. Open quarterfinals, a round or two earlier than Roddick is accustomed to succumbing to Federer.

And accustomed Roddick most certainly is, dropping to 1-14 against the man who replaced him at no. 1 in the rankings 3½ years ago and has been there since.

“I mean, I’m not walking off with any questions in my head this time. I’m not walking with my head down,” Roddick said. “I played the right way.”

Federer, though, reached his record 14th consecutive Grand Slam semifinal thanks in part by being barely better in each tiebreaker.

So, too, was Venus Williams earlier yesterday, when she came back from a set and a break down to push her quarterfinal against no. 3 Jelena Jankovic into a third-set tiebreaker. Williams was solid over those decisive points, Jankovic was slightly shakier, and the American pulled out a 4-6, 6-1, 7-6 (4) victory to get back to the U.S. Open semifinals for the first time since 2002.

Next up is a match against No. 1 Justine Henin. Know this: Venus Williams watched Henin beat younger sister Serena Williams on Tuesday and wants to right the wrong.

“I wasn’t happy with that result at all. I was sad that she lost. I didn’t like to see her so upset,” Venus said. “I definitely have to try to win for Williams.”

In the other women’s semifinal Friday, 2004 U.S. Open champion Svetlana Kuznetsova will face No. 6 Anna Chakvetadze.

Federer, meanwhile, will face No. 4 Nikolay Davydenko in Saturday’s semifinals. Federer is 9-0 against the Russian — and knows that full well.

“I’ve got a pretty good record against him. Never lost,” Federer said. “But let’s not get ahead of ourselves.”