The Americans wasted no time jumping on the Costa Ricans, as Marcia Wallis chipped the goalkeeper in just the second minute on the USA's first shot of the game to put her team up, 1-0.
Andi Sellers added another goal in the sixth minute, taking a well-placed through ball from Lori Lindsey and catching Costa Rican goalkeeper Herra Rojaso off her line. Molinaro added another goal one minute later to put the United States up 3-0 seven minutes into the game.
"It was great to get off to such a good start in our first game," U.S. midfielder Lauren Molinaro said.
The United States nearly added another in the 40th minute when a Jena Kluegel blast from 13 yards out beat Rojaso, but the ball hit the bottom of the crossbar and was cleared from danger by Costa Rica's Laura Palma.
The United States did not get on the board until the 68th minute, when Molinaro netted her second goal on a spectacular diving header after Costa Rica failed to clear a U.S. corner kick.
Then the USA's Kim Patrick took over the game. Inserted into the game in 57th minute for Andi Sellers, Patrick needed little time to adjust. In the 72nd minute she just missed a bicycle kick that instead found the side of the net from eight yards out. Just as the crowd settled back into their seats, Patrick hit a side scissors kick that glanced of the right post.
Patrick finally put one into the back of the net in the 78th minute with a rocket from 30 yards out that found the lower left corner and gave substitute goalkeeper Fernadez Villareal no chance for a save.
"I really liked the way Kim Patrick came into the game in the second half and gave us a bit of a spark off the bench," U.S. head coach Jay Hoffman said. "She and Marcia Wallis linked together real well and breathed life back into our attack."
Catherine Reddick rounded out the scoring in the 78th minute after Nandi Pryce did well to nod down a Jena Kluegel corner kick and Patrick knocked the ball in from five yards out.
Costa Rica's best scoring chance came in the fourth minute, with the score only 1-0. Melissa Lopez cranked a shot from 18 yards out that beat U.S. goalkeeper Hope Solo but hit the cross bar. Solo made three saves on the day as the Costa Ricans managed only seven shots.