As much as Jurgen Klinsmann's coaching debut with the U.S. men's national team was a promising one last month, Friday night's friendly against Costa Rica should offer even more of a glimpse into the impact the new United States manager is having on the team.

With one week to work with the squad before the match (unlike the two days he had to work with the U.S. team before the Mexico friendly), Klinsmann has had a real chance to get to know the veterans with which he will build his team, while also getting to know some of the young players who could develop into difference-makers in the run-up to the the 2014 World Cup.

Costa Rica won't offer the same challenge that Mexico did, but the match should offer a good environment for some younger players to impress and show what they can do against CONCACAF competition. Costa Rica is without standouts such as Bryan Ruiz and Celso Borges, but should still provide enough of a test for what could be a young U.S. lineup.

As much as Klinsmann spent part of the past week talking about wanting to take it slow with integrating younger players in the national team pool, the roster he has called up has the youngsters he feels are most ready for a national team close-up.

Players like MLS MVP candidate Brek Shea and Germany-born speedster Timmy Chandler are playing too well to keep out of the national team mix, and both should be showcased in the upcoming friendlies.

Shea is playing with a level of confidence and skill that has him looking every bit like a player ready for another chance to start. It was October 2010 when Shea was given his first national team start, and the forgettable turn in a draw against Colombia made him look like someone who was far away from being ready for the national team.

Shea showed just how much better he's playing with his match-turning run and pass to set up the U.S. team's equalizer against Mexico. His head-turning display, coupled with his defense-shredding form in MLS, will have Klinsmann pondering the possibilities and just how quickly to integrate a player unlike any other currently in the pool.

Chandler's return to the national team mix could be seen with a sceptical eye after he sided with his club FC Nuremberg and chose to pass up a chance to play in the Gold Cup. The decision, as well as his subsequent skipping of the Mexico friendly in August, left many questioning whether he was truly dedicated to the U.S. national team, but the fact that he's back in camp should put to rest questions about his loyalty.

Rather than Chandler's summer absences, the focus now is on his national team future and the options he gives Klinsmann. The memories of his impressive turns against Argentina and Paraguay are still fresh, and Klinsmann is surely aware of the success he has had in the Bundesliga.

Shea and Chandler, and the roles they play against Costa Rica, will get plenty of attention from U.S. fans, but those are just some of the storylines to watch for. Here are some others to keep an eye on:

Jozy Altidore's return

Altidore was playing well for the national team in the Gold Cup before a hamstring injury ended his tournament. His five goals in six games for Dutch AZ Alkmaar shows those positive Gold Cup signs were no fluke. Klinsmann deployed Edson Buddle as a target forward against Mexico. Altidore should play a similar role, and should be able to impose his will against Costa Rican defenders.

Klinsmann's systems

With two friendlies to work with, Klinsmann is likely to experiment with some different formation options. Against Mexico, we saw him work with a lone striker, but having Altidore back in the fold along with Timmy Chandler as a wing option could lead to us seeing an Altidore-Donovan forward tandem in a 4-4-2. A 4-3-3 with Altidore, Landon Donovan and Brek Shea up top would also be an intriguing system.

Castillo's second chance

Edgar Castillo had a shocker against Mexico, but it has to be noted that he struggled against some of the best attacking players in CONCACAF. He showed Klinsmann enough to merit another call, and will have a good chance to redeem himself against a Costa Rica side that isn't nearly as dangerous, but still boasts enough speed to test him.

Hamid's debut

Bill Hamid has been called up by Klinsmann for the second straight time and the 20-year-old D.C. keeper is a safe bet to see minutes considering Tim Howard is more likely to play a full 90 minutes against Belgium. Hamid is only in his first full year as a starter for D.C. United, but his size, athleticism and maturity at a young age make him the type of long-term prospect the national team needs in an uncharacteristically thin goalkeeper pool.