Petr David Josek, Associated Press
US Kerri Walsh dives for a ball during the quarterfinal women's beach volleyball match against Italy at the 2012 Summer Olympics, Sunday, Aug. 5, 2012, in London.

LONDON — Kerri Walsh Jennings' first beach volleyball coach was relentless and pitiless — a man, she said, who "thought that 21-1 was a close game."

That coach: Butch May, a 1968 indoor volleyball Olympian who happens to be teammate Misty May-Treanor's father.

"I played Misty when she was hurt," Walsh Jennings said, "and he said, 'You serve her every ball.'"

The tough-minded Americans are demolishing their opponents in London, and are advancing to the Olympic semifinals on a path to their third gold medal. Walsh Jennings and May-Treanor beat Italy 21-13, 21-13 on Sunday, and next play Beijing bronze medalists Xue Chen and Zhang Xi. The Chinese pair advanced with a 21-18, 21-11 victory over Austrian sisters Stefanie and Doris Schwaiger 21-18, 21-11 earlier Sunday.

Their approach is simple. Crush everyone.

"We want to crush everybody," Walsh Jennings said. "We don't care where they're from."

In the other quarterfinals, No. 2 U.S. team April Ross and Jennifer Kessy beat Czechs Marketa Slukova and Kristyna Kolokova. Ross and Kessy will next meet reigning world champions Juliana and Larissa of Brazil, who beat Germans Sara Goller and Laura Ludwig 21-10, 21-19 in the last match on Sunday night.

Victories on Tuesday night would set up an all-American final.

On the men's side, Americans Jake Gibb and Sean Rosenthal were scheduled to play on Monday for a spot in the quarterfinals against Latvia. The U.S. men have won three of the first four gold medals since beach volleyball became an Olympic sport in 1996. But defending Olympic champions Todd Rogers and Phil Dalhausser won't play for gold — they were knocked out in the round of 16.

Walsh Jennings and May-Treanor have won the last two Olympics, sweeping to the gold medals in Athens and Beijing without even losing a set. That's 32 sets in a row over 16 games, including their first two in the round-robin at the London Games.

But even before that straight-set streak was snapped on Wednesday, the two-time defending champions had shown signs of weakness. They lost in Moscow to China in June, then lost in straight sets in Rome to Marta Menegatti and Greta Cicolari, the same Italian pair they met in the Olympic quarterfinals on Sunday night.

The Americans are confident they've turned it around.

"I think we're a different team. We sold the old team and we bought a new team," May-Treanor said.

"For scrap," her partner piped in.

Although her nickname is "Six Feet of Sunshine," the smile disappears on the sand and Walsh Jennings can turn downright fierce in the cool London nights.

"I don't want to let our opponents breathe. I don't want to give them an edge," she said after the victory. "I don't want them to feel comfortable for one second out there."

Monday's match lasted just 33 minutes, a performance so dominating that it left opponent Menegatti in tears during a changeover.

"She was probably like, 'I don't know what to do,'" May-Treanor said. "And that's how you get teams in trouble."

Menegatti, who's 21, said she grew up idolizing May-Treanor. The Italians have only been playing together for three years, and their goal had been to qualify for the 2016 Games in Rio de Janeiro.

"She's a young player, and she'll learn" to control her emotions, May-Treanor said. "She has no reason to hold her head down whatsoever."