Serena Williams cheers on her sister Venus; the two will play together for doubles gold. (AP)

The victory extended Williams' winning streak to 32 matches, and she became only the second player to win Wimbledon, the U.S. Open and the Olympics in the same year. Steffi Graf accomplished the feat in 1988.

"I was ready to go out and take it and not just hope somebody gave it to me," Williams said. "I guess I've graduated to a different level where I can be like some of the greats."

Williams will try for her second gold when she and sister Serena play in the doubles final Thursday (Wednesday night ET) against Kristie Boogert and Miriam Oremans of the Netherlands.

Williams is unbeaten since losing at the French Open in early June, and her winning streak is the longest since Martina Hingis won 37 consecutive matches in 1997. Martina Navratilova set the record of 74 victories in a row in 1984.

Like other opponents, Dementieva couldn't cope with Williams' power. In the sixth game, the Russian barely avoided getting hit in the face by a second-serve ace.

"I wasn't ready for the second serve," Dementieva said. "It was like a first serve."

Williams wowed a crowd that included Serena and their mother, U.S. teammate and bronze medalist Monica Seles, coach Billie Jean King and members of the U.S. swim team.

Even Williams was a bit overwhelmed by the performance. When she received her medal, she beamed and covered her face with her hands.

"I felt really emotional," she said. "You see it on TV. It was really great. It was me."

Seles won the bronze Tuesday. The U.S. team lost a chance at a singles sweep when defending champion Lindsay Davenport withdrew because of a foot injury following her first-round victory.

"That was tough," Williams said. "Potentially it could have been all three of us standing there in any order."

Top-seeded Australians Todd Woodbridge and Mark Woodforde, likely playing their last match together, were upset in the final of men's doubles. Sebastien Lareau and Daniel Nestor of Canada won the gold with a 5-7, 6-3, 6-4, 7-6 (7-2) victory.

Arnaud Di Pasquale became the first Frenchman to win a tennis medal since 1924 by beating Roger Federer of Switzerland 7-6 (7-5), 6-7 (7-9), 6-3 for the bronze Wednesday.

Spaniards Alex Corretja and Albert Costa won the bronze in men's doubles, beating South Africans David Adams and John-Laffnie de Jager 2-6, 6-4, 6-3.

The 10th-seeded Dementieva, who reached the semifinals at the U.S. Open earlier this month, started well against the second-seeded Williams. The Russian won the first game and had a point to go up 2-1.

Then Williams won 15 of the next 18 points for a 5-1 lead. The serving inconsistency that plagued her earlier in the tournament was gone, and her laser groundstroke winners drew repeated gasps of appreciation from the crowd. Once, even Dementieva nodded in approval.

"It was difficult to play against her," Dementieva said. "She played very well. She's very strong."

Williams wavered after taking a 5-2 lead in the second set, losing her serve for the third time in the set. She double-faulted on the first championship point, but Dementieva then hit a backhand wide to give Williams another victory.