NEW YORK (AP) – The opening day of a Grand Slam tournament is a carnival of tennis, with more than 100 top men and women playing all across the grounds.

Storylines abound on such occasions, and Monday at the U.S. Open was no different:

• Kim Clijsters won her first Grand Slam match since being ranked No. 1;

• 1998 champion Lindsay Davenport tested her injured left foot and advanced easily;

• highly seeded players were upset (No. 8 Chanda Rubin, No. 9 Sebastien Grosjean);

• former contenders continued to fade (Greg Rusedski, Iva Majoli).

And yet, without so much as lifting a racket, one man commanded most of the attention: Pete Sampras.

The owner of a record 14 Grand Slam singles titles, including five at the U.S. Open, Sampras formally announced his retirement Monday evening, and the U.S. Tennis Association organized a ceremony to honor him at Arthur Ashe Stadium between the two night matches.

“I’m 100 percent retired,” Sampras said, his voice cracking. “I’m at peace with it. It’s time to call it a career.”

Sampras, who’s 32 and became a father in November, leaves with 64 singles titles, including seven at Wimbledon.

“I will never sit here and say I’m the greatest ever. I’ve done what I’ve done in the game. I’ve won a number of majors – I think that’s kind of the answer to everything,” he said. “I don’t know if there’s one best player of all time. I feel my game will match up to just about anybody. I played perfect tennis at times, in my mind.”

He hasn’t played at all since beating Andre Agassi to win the 2002 U.S. Open, but he never said he was quitting. His first major title also came at the Open, in 1990.

“This is something that I love to do, and I’ve been doing since I was 7,” Sampras said. “Saying ‘goodbye’ is not easy, but I know it’s time, in my heart.”

Without Sampras or the injured Serena Williams, the Open is being contested without either of the previous year’s champions for the first time in more than 30 years. It’s lent an air of anyone-can-win to both draws, and Clijsters and the third-seeded Davenport figure to be among the women who could take advantage.

Clijsters replaced Williams atop the rankings two weeks ago despite never having won a Grand Slam title and now finds herself in the role of favorite for the first time. The Belgian, only once an Open quarterfinalist, lost the first two games against NCAA singles champion Amber Liu before piecing together a 6-2, 6-3 victory.

In Davenport’s case, she’ll only be a factor if she can deal with a nerve problem in her left foot, an injury that hampered her at the French Open and Wimbledon, and forced her to quit against Jennifer Capriati during the final of a tournament Saturday.

Davenport wasn’t tested at all Monday, beating 80th-ranked Els Callens 6-1, 6-0 in 46 minutes. Davenport never even faced a break point.

“I was really relieved when the match was over and extremely nervous beforehand, just trying to figure out how my foot was going to be, and if it would be OK,” Davenport said. “It’s something I’ve chosen to deal with because I really want to play here the next two weeks.”

She’ll have surgery after the Open and should be sidelined two-to-three months.

Injuries are a recurring theme at this Open, including Williams’ left knee surgery and the stomach muscle strain that forced her sister Venus to withdraw.

Rubin has been bothered by her right shoulder, though she refused to blame that for a disjointed performance in a 6-4, 6-4 loss to Maria Vento-Kabchi, a Venezuelan ranked 84th and without a match win at a major in more than 11/2 years.

“It was just a really bad match for me,” said Rubin, who made 46 unforced errors. “I just didn’t play with enough glue. I didn’t play with enough consistency, and I didn’t concentrate well enough.”

No. 9 Grosjean, twice a Grand Slam semifinalist, did acknowledge lingering right elbow pain was part of the reason he wasted two match points and was sent home by Ramon Delgado 6-4, 6-7 (3), 4-6, 7-6 (7), 6-4.

Winners on Monday included French Open champion Juan Carlos Ferrero, 1999 runner-up Todd Martin, No. 5 Guillermo Coria, No. 9 Daniela Hantuchova, No. 13 Vera Zvonareva, No. 19 Nadia Petrova and No. 28 Lisa Raymond.

But No. 25 Eleni Daniilidou and No. 26 Lina Krasnoroutskaya lost, as did 1997 French Open champion Majoli. Other early exits were made by No. 17 Tommy Robredo, No. 18 Max Mirnyi (who was in Agassi’s quarter of the draw), and 1997 Open runner-up Rusedski, who lost to Gregory Carraz 6-4, 4-6, 6-2, 5-7, 6-4.

It was Rusedski who called Sampras “a step and a half slow” after losing to him in the third round last year. Sampras, of course, went on to win his final major title – and, it turns out, final match.

Martin spoke at length Monday about Sampras’ career. He lost 18 of 22 career matches against Sampras, including the 1994 Australian Open final.

“Pete knew when to play better, how to play better, more than anybody I’ve ever met, and I think that’s a skill and a talent that was too often veiled by the accolades that he got for his physical talents,” Martin said.

Asked if he were emotional seeing Sampras walk away, Martin smiled.

“Emotional? No,” Martin said, joking. “The guy ruined parts of my career.”