US Women start Olympic Qualifying TONIGHT #USWNT

The USA hosts CONCACAF Olympic women's qualifying for the first time in the eight-team tournament that begins TONIGHT when it hosts Costa Rica in Frisco, Texas (Streaming: 8:30 p.m. ET on NBC Live Extra).

Twelve for Rio:

Brazil

Colombia

France

Germany

New Zealand

South Africa

Zimbabwe

Asia (2)

Concacaf (2)

Europe playoff (1)

The CONCACAF field has been cleared so that 2015 Women's World Cup finalists Costa Rica and Mexico are in Group A and Canada is in Group B.

Costa Rica and Mexico should give the USA competitive matches, but the likely deciding game of tournament -- the semifinal match against Guatemala, Trinidad & Tobago or Guyana with an Olympic berth on the line -- should be a cake walk.

Olympic qualifying will be the first test of the national team since the retirements of longtime leaders Abby Wambach and Lauren Holiday and the knee injury to its most creative player,  Megan Rapinoe.

With that in mind, here are three players to follow over the next five games:

LINDSEY HORAN. Horan used the Victory Tour to quickly assert herself as a force in central midfield in place of Holiday after the latter's retirement in October. That's a new position for Horan, who was a forward for the U.S. under-20 team and at Paris St. Germain, which she joined out of high school. As long as she stayed at PSG, Horan was not going to become a fixture in the U.S. lineup, but she has all the tools to compensate to make the central midfield with Morgan Brian and Carli Lloyd the strength of the national team.

CRYSTAL DUNN. Dunn was one of two late cuts from the Women's World Cup team but wasn't deterred, turning in a MVP season for the NWSL's Washington Spirit and rejoining the national team for the fall Victory Tour. Dunn has played all over the field in her career, dating back to her days at the University of North Carolina. She looks to have first shot at a starting job in the short term because of Rapinoe's injury. Dunn might not be the playmaker Rapinoe is, but she adds pace the U.S. attack and is a capable poacher.

MALLORY PUGH. Wambach has retired and Amy Rodriguez and Sydney Leroux are on maternity leave, dashing the once-lauded depth in the U.S. attack. After Alex Morgan and Christen Press, Pugh, at the age of 17, in line to nail the No. 3 spot on the U.S. depth chart up front. She came off the bench and scored a great goal against Ireland in January. A strong tournament could put her in line for one of the 18 berths on the Olympic roster.

FOUR YEARS AGO. Four years ago, the USA won all five games in Vancouver as it clinched its fifth straight trip to the finals, where it beat Japan, 2-1, in the final to win its fourth gold medal.

U.S. Women's Roster:

GOALKEEPERS (3): 18-Ashlyn Harris (Orlando Pride), 20-Alyssa Naeher (Chicago Red Stars), 1-Hope Solo (Seattle Reign).

DEFENDERS (7): 19-Jaelene Hinkle (WNY Flash), 8-Julie Johnston (Chicago Red Stars), 7-Meghan Klingenberg (Portland Thorns), 11-Ali Krieger (Washington Spirit), 5-Kelley O'Hara (Sky Blue FC), 4-Becky Sauerbrunn (FC Kansas City), 6- Emily Sonnett (Portland Thorns).

MIDFIELDERS (5): 14-Morgan Brian (Houston Dash), 17-Tobin Heath (Portland Thorns), 9-Lindsey Horan (Portland Thorns), 10-Carli Lloyd (Houston Dash), 3- Samantha Mewis (WNY Flash).

FORWARDS (5): 16-Crystal Dunn (Washington Spirit), 15-Stephanie McCaffrey (Boston Breakers), 13-Alex Morgan (Orlando Pride), 12-Christen Press (Chicago Red Stars); 2- Mallory Pugh (Real Colorado).