Injuries left him without four regulars, including starter Geoff Cameron, and players will continue to come and go over the 11-month campaign. But for the most part, Sunday’s selections sent notice of the key figures for the consequential matches.

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The Americans will begin the 10-game rumble with two of their three most treacherous encounters over a five-day span: home against Mexico on Friday in Columbus, Ohio, and away to Costa Rica on Nov. 15. The hexagonal, as the six-nation last stage is known, will launch three teams into the next World Cup. A fourth will need to navigate a two-leg playoff against an Asian side next fall.

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The United States is seeking an eighth consecutive World Cup appearance.

Seventeen players in the current group have seen action against Mexico, 11 in qualifiers, nine in Columbus.

Before each of the next two matches, three players will be left inactive.

The current squad includes hardened veterans, such as Michael Bradley, Jozy Altidore, Fabian Johnson and Tim Howard. It also features Christian Pulisic, an 18-year-old attacking revelation for German titan Borussia Dortmund; Julian Green, 21, a 2014 World Cup scorer who has revived his Bayern Munich career this season; and MLS rookie of the year candidate Jordan Morris, from the Seattle Sounders.

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Perhaps the most surprising inclusion was Cameron Carter-Vickers, an 18-year-old center back for Tottenham Hotspur seeking his senior debut.

Players who have gained the most since the World Cup cycle restarted are D.C. United defender Steve Birnbaum, New York Red Bulls midfielder Sacha Kljestan and Hamburg forward Bobby Wood. Both Kljestan and Wood are primed to start one or both of the approaching matches.

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Midfielders Lynden Gooch (Sunderland) and Caleb Stanko (Swiss club Vaduz) have risen on the depth chart this fall. Norwegian-based Ethan Horvath, 21, is the third-choice goalkeeper behind starter Howard and back-up Brad Guzan.

The most notable absences are Cameron and Clint Dempsey. Sidelined for two weeks after hyper-extending a knee with the Premier League’s Stoke City, Cameron probably would have started both upcoming matches in central defense. Dempsey, the second-greatest scorer in U.S. history behind Landon Donovan, has been sidelined for months with a heart condition.

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With Cameron out, Omar Gonzalez is the prime option to partner with John Brooks in the heart of the backline.

Midfielders Kyle Beckerman and forward Chris Wondolowski, 2014 World Cup vets on the downside of their careers, were slated to report to camp but scratched with undisclosed injuries.

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Forward Paul Arriola, midfielder Danny Williams and left back Kellyn Acosta didn’t make the cut but will remain in the mix. Midfielder Darlington Nagbe has fallen out of favor and may no longer be in Klinsmann’s plans.

Forward Aron Johannsson returned to the fold, despite appearing in only four Bundesliga matches this season for Werder Bremen. He has been hampered by injury since the last World Cup. Midfielder Jermaine Jones, who turned 35 last week, is also back after recovering from a knee injury.

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U.S. roster

Goalkeepers: Brad Guzan (Middlesbrough), Ethan Horvath (Molde), Tim Howard (Colorado Rapids), William Yarbrough (Leon).

Defenders: Matt Besler (Sporting Kansas City), Steve Birnbaum (D.C. United), John Brooks (Hertha Berlin), Cameron Carter-Vickers (Tottenham Hotspur), Timmy Chandler (Eintracht Frankfurt), Omar Gonzalez (Pachuca), Fabian Johnson (Borussia Moenchengladbach), Michael Orozco (Tijuana), DeAndre Yedlin (Newcastle).

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Midfielders: Alejandro Bedoya (Philadelphia Union), Michael Bradley (Toronto FC), Lynden Gooch (Sunderland), Julian Green (Bayern Munich), Jermaine Jones (Colorado Rapids), Sacha Kljestan (New York Red Bulls), Christian Pulisic (Borussia Dortmund), Caleb Stanko (Vaduz), Graham Zusi (Sporting Kansas City).