American flyweight (51kg/112 lbs) Marlen Esparza defeated Venezuela's Karlha Magliocco 24-16 in Monday's quarterfinals and has secured Team USA's first boxing medal of the 2012 London Olympics.

With middleweight Claressa Shields coming from behind to capture an 18-14 decision over Sweden's Anna Laurell later in the afternoon, the U.S. women will bring home two medals from the inaugural women's boxing competition; the question is whether they will be gold, silver, or bronze.

"At first, when I got to London, it was all about just having fun and just focusing on me to do my best, because the pressure from all the attention and endorsements was done for me after I qualified," said Esparza, whose advertisements for CoverGirl and McDonald's have made her one of the more visible female faces at this year's Games. 

"But when I got there, and the rest of the team started losing, people started doubting us.  I knew the pressure was on me to get a medal for the team. Now I can relax again a little," she added.

Esparza advances to Wednesday's semifinals in a rematch with top-seeded China's Ren Cancan, who captured a 16-8 decision over the native of Houston, Tex., in the semifinals of the Women's World Championships earlier this year. Some breather.

"Well, I said a little," Esparza said, laughing. "I'll be studying some videos tonight and I'll be ready for Cancan."

Magliocco shocked Brazil's Erica Matos to reach the quarterfinals, and the pressure fighter constantly charged at Esparza to initiate exchanges.  After an 8-4 first round for Esparza that seemed closer than the score indicated, the American began to find holes in her foe's armor.

"I knew she was really, really aggressive, and a wild punching fighter. so I wanted to make sure she didn't think she could attack,e whenever when she wanted to," Esparza said.  "I wanted to set the tone early, so I hit her a couple times to the body.  She calmed down for a while, but it's like she had a deathwish because she kept coming forward."

Esparza would gradually pull away from Magliocco, putting on a fine exhibition of alternating between boxing and punching while amassing leads of 14-8 and 19-12 following the second and third rounds.  Despite the considerable lead, Esparza refused to leave anything to chance in light of the controversial decisions that have rocked the sport over the past week, and continued to slug it out with her Venezuelan opponent.

When the final score was announced, Esparza was satisfied with the win but still felt her performance left a little to be desired.

"I really wanted to do better with my jab, but for a month I’ve been practicing against left-handers," she said. "That was like the first time in a month I was in with a right-hander. It threw me off a little, but I started going with my right overhand (punch) more because it was comfortable, and it worked out."

The winner of Cancan-Esparza will move on to Thursday's gold medal final, while the loser will be automatically awarded bronze, as there is no third-place bout in Olympic boxing. Esparza is confident that Cancan has yet to see the best version of her, especially given the circumstances behind their last matchup.

"She hasn’t seen the best of me," Esparza said.  "I'm 100 percent sure of that.  The last time we fought at worlds, the goal was just to qualify for the Olympics, and it was hard to get fully motivated since I had already accomplished that.  Now it's about the gold medal, and I'm going for it."