Chances to impress growing precious and few; U.S. faces Bosnia-Herzegovina in a friendly in Sarajevo

• Several important U.S. starters will sit this one out
• The Eastern European nation is 13^th in current FIFA rankings
• Tim Howard, Michael Bradley and Jozy Altidore are the U.S. headliners

Jurgen Klinsmann has tinkered for more than two years now, experimenting with personnel and formations while working the levers to find the very best version of the current United States national team.

But time is growing short before the U.S. boss, now blessed with the nodding approval of most American soccer fans, begins closing out this “experimental phase” and looking to tighten up the operation. That means chances to impress will be precious and few going forward.

In fact, Wednesday’s friendly in against Bosnia-Herzegovina may be the one and only chance remaining for some of the faces who arrived into Sarajevo on Monday for a few quick practices and the mid-week match inside Asim Ferhatovic Hase Stadium. Kickoff on ESPN2 is set for 2:30 p.m. ET.

Klinsmann has summoned mostly European-based player to face the world’s 13^th-ranked team according to FIFA. Bosnia-Herzegovina currently tops its World Cup qualifying group, although it’s a relatively weak assembly.

Everton goalkeeper Tim Howard, Roma midfielder Michael Bradley, Schalke midfielder Jermaine Jones and Sunderland striker Jozy Altidore (who is currently on a four-game scoring streak, a signature accomplishment at international level) are the front-line U.S. men in this particular group. Expect all to start.

Beyond them, there may be four U.S. men in Sarajevo who have more or less secured their spot for Brazil next year. (The United States has a place all but mathematically booked for the 2014 World Cup; expect that to happen during the pair of qualifiers coming up in early September.)

(MORE: Hearing from Jurgen Klinsmann on the Clint Dempsey omission)

That means the bulk of Wednesday’s 22-man roster – it was 23 before a hamstring injury removed center back Michael Orozco Fiscal from consideration – still has some proving ahead. A few of the ‘tweeners, like Eddie Johnson or Sacha Kljestan (pictured), are better positioned than others for spots on the 23-man World Cup roster.

But for a formerly forgotten man like Tim Ream, in his first U.S. camp in almost two years, or for versatile defender-midfielder Brad Evans, this chance is pure gold. If they get time, which seems especially likely in Ream’s case, they simply must make an impression on the boss.

Same goes for four youngsters getting their initial, up-close inspection from Klinsmann. They are mostly here for introductions into the full program, but that doesn’t mean they can’t surprise the coach with a special performance, if they happen to get on the field.

Among that foursome is promising center back John Brooks and Iceland-raised striker Aron Johannsson, whose paperwork from FIFA arrived only on Tuesday afternoon.

(MORE: Chances just increased of seeing Aron Johannsson on Wednesday)

This may be another chance for Geoff Cameron to prove his value as Klinsmann’s potential utility knife on next year’s roster. Having recently shown he can be a holding midfielder at international level, and having demonstrated in the Premier League that he can hold his own at right back, a shortage of center backs may require the former Houston Dynamo to take up his old spot in central defense Wednesday.

(MORE: Michael Orozco Fiscal withdraws due to injury)

Most of the MLS-based national team regulars aren’t in Sarajevo. That group includes Landon Donovan, commanding star of the show during the United States’ recent Gold Cup crowning, and Clint Dempsey, who just made a head-spinning move from England’s Tottenham to the Seattle Sounders of MLS. For a mid-week contest, and considering the MLS types are so critical to their teams’ ongoing playoff push, Klinsmann left them stateside for this one.

The United States remains on its record 11-match winning streak, which began June 2 with a 4-3 victory over Germany.

(MORE: A few notes and conclusions from U.S. roster announcement)