Two months after enchanting this city with her electrifying win at the U.S. Open, Serena Williams left New York disappointed today after pulling out of the WTA Tour's season-ending Chase Championships with an upper back injury. Williams said she had been practicing forehand volleys on the indoor court at Madison Square Garden this morning when she felt an "excruciating pain" that was later diagnosed by the tournament doctor as vertebral dysfunction.

"I didn't feel anything pop or pull, but all of the sudden I couldn't move, run, walk, and even the simplest task of breathing became nearly impossible," said Williams, who was seeded fourth. "This was the first year I've qualified for the Chase--I can't believe this had to happen."

Williams has played only two tournaments since winning the Open in September, but when asked whether her sparse schedule had anything to do with the injury, Williams's father, Richard, said: "No, that doesn't have anything to do with it--Serena just doesn't take care of herself, stretching and things. She's supposed to stretch."

In fact, Richard said he does not think either Serena or her sister, Venus, should cut down on their fashion design classes at a local Florida college in order to play more tournaments. Of Venus, he said: "If you could see how good her grades are and she is ranked number three in the world--I don't think you could ask for more than that. If anything, Venus should cut down on a couple of tournaments. The truth is that if you have a child at 19 who's listening [about education], and--forgive me for saying this--a girl, too, you should leave her alone."

Venus, who withdrew from this tournament because of tendinitis last year, is scheduled to meet Conchita Martinez in the first round Wednesday. Serena's injury has forced the Williamses to pull out of the doubles draw, and Serena was replaced in the singles draw by 18th-ranked Elena Likhovtseva, who lost to Dominique Van Roost, 6-2, 6-3, in a first-round match tonight. Defending champion Martina Hingis also played, fighting to defeat Sandrine Testud, 7-6 (7-5), 7-6 (7-5), although the evening's most celebrated moment came when the WTA honored Steffi Graf in a ceremony.

Graf, who retired this year after a 17-year professional career, was given several gifts, including a chunk of the original court from the U.S. Open's Louis Armstrong Stadium and a diamond solitaire from Madison Square Garden. Graf was emotional during the ceremony, tearing up during a lengthy crowd ovation, then jumping up and down in excitement a few minutes later when she was presented with a plank of wood from her favorite locker at the French Open.

The presentations ended with former New York Knick Earl Monroe helping Graf raise a banner with her name on it into the rafters of Madison Square Garden. The banner will be displayed during tennis events, and Graf was thrilled with the honor.

"Look up here," she said, pointing. "This is just overwhelming, incredible. All the things that have been said, the presents that I have received--I want to thank everyone. . . . I'll miss you all."

Midway through the ceremony, one member of the crowd shouted out "Where's Andre?" referring to Graf's highly publicized romance with men's No. 1 Andre Agassi. Graf started laughing as the crowd cheered, answering: "He's probably at home, watching. You don't want to mess with him."

If anyone could relate to Serena Williams's plight this morning it was Graf, who battled injuries throughout her career. This is the fifth time this year Serena has missed a major tournament with a last-minute injury or illness; her most noted absence was her withdrawal from Wimbledon with the flu. In the 12 tournaments she has played, however, she has been phenomenal, winning five titles and climbing to the No. 4 world ranking.

Serena was treated this morning by WTA trainer Kathleen Stroia and tournament doctor Ken Montgomery, who prescribed anti-inflammatory medication, massage therapy, special exercises and rest.

"Serena had temporary relief following the treatment, but pain returned shortly," Stroia said. "Obviously rest and treatment are required for the injury to heal."

Williams is the second player to withdraw from the tournament; three-time winner Monica Seles withdrew last week with a foot injury.