NEW YORK (AP) Janko Tipsarevic is still eating gluten. Some other ingredients - on the plate and on the court - have been cut out of his life as he's ascended to his highest ranking.

The 20th-seeded Serb matched his best Grand Slam result by reaching the fourth round of the U.S. Open on Saturday. Tipsarevic was leading 6-4, 5-0 when ninth-seeded Tomas Berdych retired.

At 27, Tipsarevic is three years older than top-ranked Novak Djokovic, but he considers his countryman a bit of a role model. Perhaps it's not a coincidence that both are having career years.

``I am extremely grateful for having Novak as a part of my life, because I have a chance to look from a front row seat what the world's best tennis player is doing,'' Tipsarevic said.

Tipsarevic took a food intolerance test and found he didn't have to go gluten-free like Djokovic. But he learned he was sensitive to other ingredients and has dropped milk, eggs and juices from his diet.

There were also some other, bigger changes.

Maybe just at the time I didn't want to sacrifice my free time in my life,'' Tipsarevic said.I'm doing things differently this year. I'm completely dedicated to tennis, which was not the situation a couple years back. I was choosing to do some other things before going to bed on time or doing stretching after every practice or hitting the gym every time that I need to.''

Before, he said, ``I was always playing the sport just to enjoy the time being on tour, winning points, winning money and all that.'' This year, he set a goal to be in the top 20 at end of the season.

I guess I was kind of sick being all the time around 30 or 40,'' Tipsarevic said.I am not getting any younger. I'm not old but I'm not young. I see guys from my generation like (Robin) Soderling or (Gilles) Simon had their, if I can say, dreams come true, winning tournaments, being top 10. I feel that I have the quality. It's just the thing is that my head was not there in the previous years.''

Tipsarevic next faces unseeded Juan Carlos Ferrero, who also advanced when his opponent retired while trailing. Tipsarevic upset Andy Roddick in the second round at last year's U.S. Open, but was knocked out by Gael Monfils in his next match.

He's twice lost in the fourth round at major tournaments, both at Wimbledon.

I'm not a fan of giving big statements. I don't like to say, 'This is my time to shine,' or whatever,'' Tipsarevic said.I know it's overrated and it's a cliche to say, because you guys heard it so many times before, but I really, really want to focus just on the next match, because I had chances before twice playing fourth round in Wimbledon against really beatable opponents, and I just screwed it up at the end because I was thinking too big, that I have a chance to play semis or something.''


PANCHO HONORED: Back in the 1950s and '60s, Pancho Gonzalez was one of the handful of players who bought into a novel idea - that you could play tennis for money.

During an era when the Grand Slam tournaments were closed to professionals, Gonzalez was one of the most successful players on the fledgeling professional tours - groups of six to 10 players who barnstormed around the country and the globe, playing to small crowds for prize money.

On Saturday, in an honor many felt was long overdue, Gonzalez was posthumously inducted into the U.S. Open Court of Champions, a hallowed spot at the National Tennis Center that honors the game's great players. Gonzalez is in there with the likes of Arthur Ashe, Don Budge, Jimmy Connors and John McEnroe, all of whom won their fair share of Grand Slam events.

Gonzalez won America's Grand Slam twice, as well, back in 1948 and 1949, but turned pro and, as such, was barred from playing the biggest events for nearly two decades.

Because of that, it's hard to pinpoint his place on the list of greats, though tennis historians agree he's squarely in the top 10. Gonzalez was long thought of as the top one or two among the pros he toured with in the 50s and 60s - Budge, Pancho Segura, Tony Trabert and Lew Hoad, among them.

Imagine today if you took the top eight pros in the world and they had to play each other every day and every week,'' said Gonzalez' son, Dan.But their passion and love for the game overtook everything they did. They created that image. Gradually, each year, the crowds became bigger, the interest was better and it became a bona fide sport. They're the ones who put it out there, showing people that tennis was the real thing.''


YOUNG GUARD: The Americans' young guard beat the old in mixed doubles.

Jack Sock and Melanie Oudin upset the top-seeded defending champs, Bob Bryan and Liezel Huber, 2-6, 6-3, 10-6 (tiebreak).

The 19-year-old Oudin was the darling of the 2009 U.S. Open, reaching the quarterfinals. The 18-year-old Sock earned his first Grand Slam victory in the first round this year before being eliminated by Andy Roddick on Friday.

Their combined age is 37. Huber is 35 and Bryan 33.

It was a rough tournament for the Bryan brothers. Bob and his twin, Mike, were also the top-ranked defending champs in men's doubles - and they were also upset in the first round.


AP National Writer Eddie Pells contributed to this report.