The Americans are hoping to register their first-ever away victory over Costa Rica in the qualifying final round, and three days later they will face Honduras on home soil.

Later in June, USA will fly to South Africa to take part in the Confederations Cup.

"Clearly these matches (qualifiers) are very important in our efforts to qualify," said Bradley.

"We are certainly aware of the challenges of playing in Costa Rica and Honduras has produced some great results."

Bradley is yet to include two more players to roster, which should be trimmed to 23 men.

USA, so far unbeaten, are leading the CONCACAF qualifying table with seven points, one ahead of Costa Rica.

Bradley's team lie in the Confederations Cup Group B alongside Italy, Egypt and Brazil.

Squad:

Goalkeepers: Brad Guzan (Aston Villa), Tim Howard (Everton)

Defenders: Carlos Bocanegra (Rennes), Jonathan Bornstein (Chivas USA), Danny Califf (Midtjylland), Jay DeMerit (Watford), Frankie Hejduk (Columbus Crew), Oguchi Onyewu (Standard de Liege), Heath Pearce (Hansa Rostock), Jonathan Spector (West Ham United), Marvell Wynne (Toronto FC)

Midfielders: Freddy Adu (Monaco), DaMarcus Beasley (Rangers), Michael Bradley (Borussia Mönchengladbach), Maurice Edu (Rangers), Benny Feilhaber (Aarhus), Sacha Kljestan (Chivas USA), Pablo Mastroeni (Colorado Rapids), José Francisco Torres (Pachuca)

Strikers: Jozy Altidore (Xerez), Brian Ching (Houston Dynamo), Charlie Davies (Hammarby), Clint Dempsey (Fulham), Landon Donovan (Los Angeles Galaxy)