LONDON -- Flyweight Marlen Esparza moves the way a hornet would if it stood upright and wore size-5 shoes. Middleweight Claressa Shields has the lethal aura of a big cat lying in wait, then striking more quickly than the eye can follow.
Esparza is tactical and calculating. Shields embodies power and emotion. Separately and together, they're figurative descendants of the American titans whose personalities -- as big as any cross or uppercut -- have historically captured the imaginations of casual fans.
Both are guaranteed Olympic medals in Wednesday's semifinals after having won their Monday quarterfinal fights in the inaugural women's boxing competition, because of the sport's tradition of awarding double bronzes. But neither wants to end up with that color from the crayon box.
"In the U.S., if it's not a gold, it's not good enough,'' said Esparza, a 23-year-old Houston native who outclassed and outfinessed her opponent, Karlha Magliocco of Venezuela, in each of their four two-minute rounds.
Shields, the 17-year-old phenom from Flint, Mich., kept referring to "my gold medal'' with a bravado that her famous sporting forebearers would appreciate. In the midst of talking to reporters after her come-from-behind win over two-time world champion Anna Laurell of Sweden, Shields paused and listened to the public address system as the result of another middleweight fight was announced. She did a little twirl and grinned.
"I wanted to fight Mary [Spencer, of Canada], but she lost,'' Shields said. "She was calling me out.''
It'd be somewhat of a stretch to say the women's success would compensate should the U.S. men be shut out of medals for the first time in Olympic history. The female draw is so small -- 12 athletes in each of three weight classes, as opposed to the men's side, where up to 30 compete in 10 -- that it still feels like an experiment. Shields and Esparza both received byes in the first round, and thus clinched medals after winning just one fight.
But in another way, all the women boxing here feel pressure to put on a riveting show in a short time. They want to be in Rio four years from now in greater numbers. The case they made at the ExCel Center on Monday was convincing.
At a Summer Games where empty seats have been a talking point, the 10,000-seat hall in the ExCel center was sold out. When Irish star Katie Taylor took on Great Britain's Natasha Jonas, the joint reverberated with deafening cheers and singing that, with closed eyes, easily could have passed for the soundtrack of a world-class soccer match.
The short-lived notion that the women should be made to wear skirts -- which arose in part because officials worried they couldn't be distinguished from men at a distance or on television -- was misguided from the start, but the action here over the past two days has torpedoed any doubt. Fans at the Olympics will turn out to watch good fighters, period.
"I thought the crowd was going to freak me out a lot more than it did,'' Esparza said. "'Oh my gosh, all these people, what am I doing? I wanna go home!' They were booing a lot. Why? That pissed me off a little bit, so that helped.''
Esparza's high-wattage smile and articulate speech have made her a marketer's darling. She doesn't have the hardscrabble backstory that is so familiar to this sport, but she's tough anyway -- a good thing from a big-picture viewpoint from a sport that would love to attract more diverse participation and audience.
Shields hails from a downtrodden city that has produced more than a few great athletes and also eats its young with frightening frequency. She told reporters she has lost four boxing friends to gun violence, the latest only last week, and believes, like so many men before her, that she's been rescued by the sport.
"Boxing definitely kept me in line,'' she said. "With the kind of attitude I have, ferocious attitude, if I was to put all my energy up into something negative, I would be just as powerful as I am in boxing.''
Shields' father, who served time in prison when she was a child, first suggested and then withdrew the idea that she should box like Muhammad Ali's daughter Laila, but it was too late -- Claressa already had her teeth into it. He is totally supportive now and likes to pump her up before fights by telling her to imagine she's a little girl getting bullied by a bigger one who steals her bicycle or takes the hamburger off her plate at McDonald's.
"It's a made-up story,'' she said. "Don't nobody take nothing from me.'' And then she cracked up.
Watching women do empowering things on a field of play is, thankfully, no longer a novel experience. But hearing Esparza and Shields talk about why they love what they do -- expressing sentiments that would have been unthinkable a couple of generations ago -- is still groundbreaking. They are on the front line; they don't have a Pied Piper like Mia Hamm or years' worth of icons to compare themselves to.
Asked to list the boxers she admires, Shields reeled off Joe Louis, Sugar Ray Robinson, Sugar Ray Leonard and Tommy Hearns. None of them ever had to wonder whether they'd sell out an arena or be made to wear something more eye-catching. These women are fighting for their immediate future.
"I box for a lot of reasons,'' Shields said, launching an impromptu manifesto that could have come from either gender in any era.
"To show you can come from a real small city where you're not really acknowledged and then you can become something. And then I look at -- I'm really fighting for my family. I love them, and I feel like boxing is gonna help me be able to take care of them. ... I want to win. I want to be successful. And that's why I box.''