Serena Williams got her apology yesterday for a blown line call during her quarterfinal loss to Jennifer Capriati, and she deserved it. But she also deserved to lose.

As the rain fell yesterday and the dust settled from Tuesday night’s controversial match, Arlen Kantarian, the chief executive of professional tennis for the United States Tennis Association, said he spoke to Williams about the conduct of Mariana Alves, the chair umpire who called a backhand winner from Williams wide even though a linesman called it good. The ball was on the other side of the court from Alves, and replays showed the shot was clearly good and seemingly inside the line.

“I told [Williams] she was a class act,” Kantarian said. “We apologized for the mistake.”

Alves herself will not write a letter of apology as Williams had asked, according to Jim Curley, the tournament director.

“I don’t think that’s appropriate for a chair umpire,” he said. “She did the best she could under the circumstances, and we move on.”

Indeed, it was a stupendous blunder, coming on deuce in the third set of a tense match. Two more questionable calls marred the last game of the match, but those were made by linesmen.

Alves, who is from Portugal, was not available for comment yesterday, and Curley said she had been relieved from duty for the rest of the tournament.

With Alves nowhere to be found yesterday, the questions for Kantarian and Curley were fast and furious, most of them about when tennis would adopt instant replay and what technology was available to cut out – or at least reduce – errors from human eyes tracking balls that fly back and forth at more than 100 miles an hour.

The technology already exists on television. USA Network’s HawkEye uses a series of precisely placed cameras to create a digital map of the court and the ball. The results are instantaneous – unless the cameras are obstructed – and the technology makes for great viewing. The USTA, however, is not convinced that it’s good enough to rely on during matches.

“We’re not convinced that it’s 100% accurate,” Curley said. “We understand that there is an error factor on Hawk-Eye, possibly a couple of centimeters.”

Then there is “Auto-Ref,” a developing technology that combines high-speed digital cameras with computer software to call lines, measure the speed of balls, and create digitally animated replays.

The technology was tested during the Open’s qualifying tournament and Curley said that the USTA, along with officials from the men’s and women’s tours and the International Tennis Federation, would take stock of it after the tournament. Still, no timetable was offered for sanctioning any of these tools, and Kantarian said a lot of testing needed to be done first.

Whatever the technology, Williams would have lost Tuesday night. She hit 57 unforced errors to 29 for Capriati. The jarring number of mistakes was none too surprising considering Williams’s play of late. She made just 17 errors in each of her first two rounds, but she sprayed 42 of them in the third round against a tenacious Tatiania Golovin, seeded 30th, in a 7-5, 6-4 victory, a score that was a lot closer than it should have been.

“Serena got some bad calls,” Patrick McEnroe said yesterday. “But she made 57 errors, and a lot of those were because Jennifer was scrappy and clawing and fighting. I thought [Capriati] deserved to win the match.”

Williams did lose her serve on the first game of the third set when Alves made her ghastly overrule, but she broke back the next game. More telling were the details of Williams’s next service game, which she lost at 15-40.Every point Capriati won resulted from an unforced error.

Trailing 3-2, Williams made a backhand error after working her way to break point. Two games later, with Capriati leading 4-3, Williams jumped out to a love-30 lead, but made a backhand error and missed a forehand chance on a Capriati second serve. Capriati held that game at 40-30 with what might have been her best point of the night, as she sprinted side to side and worked her way back into a rally with a slice backhand until Williams misfired again.

Williams had knee surgery last year, and she’s had recurring problems with the injury this year. As her off-court interests have become more various, her dedication to tennis has been questioned, though she maintains she is still hungry for a return to dominance. Whatever the case may be, Williams is not the player she once was, and it may be a while before she begins resemble her former self.

It should be added that Capriati, who has struggled all summer with injuries and erratic play, did not even bring her best tennis to the court Tuesday night. If Lindsay Davenport had been out there, chances are Williams would have been beaten handily.

Bad calls or not, it was a big victory for Capriati in a disappointing seasons, one that she won with willpower rather than blistering strokes. In the record books, it shouldn’t exist with an asterisk next to it.