The United States hammered Costa Rica in their opening match at the CONCACAF Women's Olympic Qualifier ©Getty Images

Reigning Olympic champions the United States began their pursuit of a place at Rio 2016 in style as they thrashed Costa Rica 5-0 in their opening Group A match at the Confederation of North, Central America and Caribbean Association Football (CONCACAF) Women’s Olympic Qualifying Tournament at the Toyota Stadium in Frisco, Texas.

The hosts, whose build-up to the competition was dominated by a row with governing body US Soccer, who have filed a law suit against the team in order to stop them going on strike ahead of this year’s Olympics, got off to the perfect start as Alex Morgan broke the deadlock after just 12 seconds.

It was the quickest goal ever scored at the CONCACAF tournament and set the American side on their way to a commanding victory.

Carli Lloyd, who scored a hat-trick in last year’s FIFA Women’s World Cup final win over Japan, doubled her side’s advantage from the penalty spot after Crystal Dunn had been brought down in the area.

With just 15 minutes gone, the United States appeared to have the three points all but sewn up as Dunn bundled home a scrappy third.

They had to wait until just after the hour mark to find a fourth and it came thanks to Morgan, who found space before guiding a header from Lloyd’s cross into the net.

Maribel Dominguez scored a hat-trick as Mexico thumped Puerto Rico 6-0 in the other Group A match today
Maribel Dominguez scored a hat-trick as Mexico thumped Puerto Rico 6-0 in the other Group A match today ©Getty Images

The rout was then complete when Christen Press made Costa Rica pay for allowing her to turn inside the box as she added her name to the scoresheet with the fifth American goal.

In the other match in the group, veteran striker Maribel Dominguez netted a hat-trick as Mexico hammered a hapless Puerto Rico 6-0 to fire themselves to top spot in Group A.

The Mexicans dominated proceedings from the outset and Alina Garciamendez, Nayeli Rangel and Katlyn Johnson also got in on the act to round off a confident display.

Mexico are bidding to reach their first Olympic Games since Athens 2004, where they were eliminated at the quarter-final stage following a 5-0 reverse at the hands of Brazil.

The two sides who book their place in the final of the CONCACAF will earn a berth at Rio 2016.

The tournament in the United States continues tomorrow when Guatemala entertain Trinidad and Tobago and Canada clash with Guyana, with both matches due to take place at the BBVA Compass Stadium.