New York ? Serena Williams was robbed of a point by an umpire’s mistake at the U.S. Open, just like her sister was at Wimbledon.

It happened in the opening game of the third set between Williams and Jennifer Capriati, who went on to win their Open quarterfinal, 2-6, 6-4, 6-4, Tuesday night.

“I’m very angry and bitter right now. I felt cheated. Shall I go on? I just feel robbed,” a composed Williams said, laughing a bit. “At first, I thought it was another Wimbledon conspiracy.”

Capriati played superbly, without a doubt, but what will be remembered is the miscue by chair umpire Mariana Alves of Portugal. She awarded the point to Capriati after Williams hit a backhand that landed in — and was ruled good by the line judge.

“I don’t need to see the replay. I know my shots. Not only was it in, it wasn’t even near the line,” said Williams, who couldn’t defend her 2002 Open title because of knee surgery that forced her to miss eight months. “But I’m not making excuses. I didn’t lose because of that. I probably should have closed her out in the second set.”

It was eerily reminiscent of Wimbledon, where Venus Williams lost in the second round after Karolina Sprem mistakenly was awarded an extra point in the final-set tiebreaker. Venus didn’t argue at all, saying later she was confused; chair umpire Ted Watts was kicked out of the tournament.

Alves won’t officiate another match during the Open, said tournament referee Brian Earley, who acknowledged the overrule by Alves was wrong.

Williams wound up losing that pivotal game, and though she did break right back, she was broken again to 2-1 and never recovered. TV replays also appeared to show at least two other incorrect calls that went against Williams in the final game, when Capriati needed three match points to serve it out.

In the semifinals, eighth-seeded Capriati will face No. 6 Elena Dementieva, who outlasted No. 2 Amelie Mauresmo, 4-6, 6-4, 7-6 (1). Mauresmo would have clinched the No. 1 ranking if she had won.

Defending men’s champion Andy Roddick assembled a 6-3, 6-2, 6-4 victory over No. 18 Tommy Robredo to reach the quarterfinals. Roddick’s next foe is No. 28 Joachim Johansson, who beat Michael Llodra, 6-2, 6-3, 6-2.