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VANCOUVER, British Columbia -- The U.S. women's soccer team was still on the field, having dispatched rival Mexico, when Abby Wambach gathered her teammates for a little speech.

The message: "We haven't done anything yet."

The Americans avenged one of their most shocking losses Tuesday night, and did so emphatically. A pair of early goals put to rest any notion of another upset by the neighbor to the south, and Carli Lloyd scored her first international hat trick in a 4-0 victory that clinched first place in the Americans' group and put them a major step closer to the London Olympics.

But hang on. Next up is the one game in this tournament that matters most, the London-or-bust semifinal against Costa Rica on Friday. The winner gets one of the two available berths for the Olympics; the loser stays home.

"The next game is the game that we need to be prepared for and that matters the most," goalkeeper Hope Solo said. "She made sure that we didn't celebrate too much today."

Wambach and her teammates remember all too well the sting from a 2-1 defeat against Mexico in Cancun in a World Cup qualifier 14 months ago, the only time in 28 tries the Mexicans have beaten the Americans. That loss forced the U.S. into a backdoor playoff just to qualify for the World Cup -- and served as a wake-up call that the top-ranked team in the world can't take important games for granted anymore.

"This was the exact same position that we were in, in Mexico in 2010," Wambach said. "We haven't done anything. We still have one game left. That's what I said -- stay focused.

"It's simple. I think everybody knows it. I think everybody understands it. But I also think that in hindsight we wish we had said something like that prior to that game. Because we didn't say those things, I didn't want to leave any stone unturned. And that's kind of what that speech was about."

[+] EnlargeRich Lam/Getty ImagesThe U.S. players, including Heather O'Reilly, wrote 'liebe' -- German for 'love' -- on their arms as a tribute to Ali Krieger, who suffered two torn knee ligaments Jan. 20.

The Americans will be heavily favored in the semis. Costa Rica is ranked No. 41 in the world and has never beaten the U.S., having been outscored 34-0 in seven meetings. Had the Americans lost to Mexico on Tuesday, they would have faced a much tougher semifinal against host Canada.

Instead, it will be Mexico versus Canada in the other semi that will produce the tournament's second Olympic berth.

The lessons from Cancun have been prevalent during this entire CONCACAF tournament. The Americans routed their first two opponents -- the Dominican Republic and Guatemala -- by scores of 14-0 and 13-0, the most lopsided results in U.S. team history.

Keeping with that theme, coach Pia Sundhage wanted a strong start against the Mexicans, and she got one. The Americans controlled the run of play early, and it paid off when Lloyd headed in the rebound in the seventh minute after Rachel Buehler clanged a shot off the post following a corner kick.

A minute later, the lead was doubled. Amy Rodriguez's cross was deflected by a defender and then by goalkeeper Cecilia Santiago straight to Heather O'Reilly for an easy goal.

Lloyd also netted in the 57th and 86th as the Americans avoided a repeat of a Mexican upset -- and wrapped up group play with three wins by a combined score of 31-0.

"It was redemption for us," Lloyd said. "We came out strong and knew we had to get it done."

The Mexicans, buoyed by a vocal and slightly pro-Mexico crowd of 7,599 at BC Place, worked hard on the counterattack for a goal, but the American back four of Buehler, Becky Sauerbrunn, Christie Rampone and Amy LePeilbet cleared nearly every serious threat, leaving Solo without much work to earn her third shutout of the tournament.

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That was probably for the best. Solo revealed after the game that she has "a little quad pull" that nearly caused her to ask for a sub. She hopes she'll be fine for the semifinals.

The defensive performance was especially heartening for the Americans given the absence of Ali Krieger, who tore two ligaments in her right knee against the Dominican Republic and likely won't be back in time for the Olympics.

As a tribute to Krieger, each American player had the word "liebe" -- German for "love" -- written on her arm. Krieger, who has played five seasons in the German league for FFC Frankfurt, has a tattoo with the word on her left arm.

"Ali will be a part of this team -- whether she's here or not," Wambach said.