BEIJING — Italy's Giulia Quintavalle won an upset-filled women's 57-kilogram class at the Olympics on Monday and Azerbaijan's Elnur Mammadli avenged his loss last year to Wang Ki-chun of South Korea in the men's 73-kilogram class.

Quintavalle took the early lead against Deborah Gravenstijn of the Netherlands and then expanded on it with a throw with just under two minutes remaining. Gravenstijn, ranked 8th in the world, could not find an opening, and was held scoreless until the five-minute match ended.

"I fought a tactical fight," Quintavalle said. "But I knew I could win."

Winning the bronzes were Brazil's Ketleyn Quadros, who defeated Australia's Maria Pekli in overtime, and China's Xu Yan, who upset No. 2-ranked Barbara Harel of France.

The men's final was over almost as soon as it started.

Mammadli needed only 23 seconds to finish off Wang, who had injured his ribs in the quarterfinal.

"It is a fight," Mammadli said. "He was the winner in the world championships. I am the winner now."

Winning Tajikistan's first Olympic medal ever, Rasul Boqiev threw European champion Dirk van Tichelt, of Belgium, for an ippon win and a bronze.

The second bronze went to Brazil's Leandro Guilheiro, who also needed less than 30 seconds to end his medal match with an ippon throw over Iran's Ali Malomat.

The women's field was exceptionally strong, and the preliminaries quickly decided the fate of several of the top athletes.

Gold-medal favorite Kye Sun Hui, the Atlanta extra-lightweight champion, threw Austria's Sabrina Filzmoser, the European champion and No. 1-ranked this year, with an ippon in her first match. But the North Korean then lost to Harel, by waza ari.

After coming back in repechage, Harel was stunned by China's Xu, who, after trailing, unleashed a throw that twirled her to the mat. As the crowd roared at Beijing's Science and Technology University, Xu did several backflips to celebrate her medal.

Quintavalle, who moved down from 63 kilograms 1 1/2 years ago, opened with a victory over Athens gold medalist Yvonne Boenisch of Germany, then defeated Harel for her semifinal berth against Australia's Pekli.

"Yvonne had lost against this opponent already at the past world championships," said Norbert Littkopf, Boenisch's coach. "It was a tough draw for everybody."

Third-ranked Isabel Fernandez, the Sydney gold medalist, went into overtime with Valerie Gotay of the United States in her opening bout and won on points. But she lost her next bout and did not medal.

"I want to congratulate the new generation," said silver medalist Gravenstijn. "It's good for judo."

The men's was a more scattered field, with the gold and silver medalists from Athens not in the running.

But in a match worthy of a final, Mammadli threw van Tichelt for an ippon halfway through their first-round match.

Wang slowed visibly after his quarterfinal, narrowly getting past Boqiev in the semis, on points.

He was virtually defenseless in the final.

Japan, which has been struggling in recent world competitions, was not a factor Monday.

Yusuke Kanamaru, third in the world championships but making his Olympic debut, crashed down to an ippon to Malomat in the first round. Kanamaru was eliminated from medal territory by Belguim's van Tichelt.

Kanamaru said he has had enough.

"I had already decided to retire after these games, but I will talk to the people around me and make my final decision."