For the better part of the past dozen years, any time the U.S. men's national team faced Mexico, the heated rivalry and battle for regional supremacy served as the dominating and adequate storyline.

As the squads prepare to meet yet again, on Wednesday in Philadelphia, the center of attention isn't American or Mexican, but German. Jurgen Klinsmann's long-awaited arrival as U.S. head coach has overshadowed a match that suddenly doesn't seem to have the same focus points it might have had if Bob Bradley were still manning the U.S. sidelines.

The match itself still has plenty of significant, but for far different reasons. Now, instead of being about beating Mexico, Wednesday's friendly is about getting the first glimpses of the Klinsmann era and of what sort of influence he might already be having on a team that hadn't been putting up the best results over the past year.

The squad Klinsmann called in has several familiar faces, but it is clear in some of the names he has called that he is eager to get started on familiarizing himself with some players who either hadn't gotten much of a look under Bradley, or who hadn't played key roles recently.

How those new faces do against Mexico could help determine whether Klinsmann's U.S. national team debut is a successful one, but the reality is Wednesday's USA-Mexico match isn't as much about getting a result as it is about seeing how U.S. players, both veterans and newcomers alike, respond to Klinsmann's coaching style and tactical approach, and whether some new options are ready to take on bigger roles in the Klinsmann era.

These are just some of the things to watch for from Klinsmann's U.S. national team coaching debut on Wednesday night:

Landon Donovan could be handed a new role by Jurgen Klinsmann. (Andy Lyons/Getty Images)

Landon Donovan's role

Jurgen Klinsmann has talked about wanting a more attacking style, and has also mentioned wanting to get Donovan closer to goal. There is a very good possibility Klinsmann will use Donovan differently, potentially as a forward or in the hole. The Mexico match should shed light on where Klinsmann believes Donovan can do the most damage for the United States.

The left-back candidates

Anyone who watched the Gold Cup knows just how few left back options the U.S. has, but it's clear Klinsmann wants to take a look at new faces there. With Carlos Bocanegra looking more likely to play centerback against Mexico, we could see Edgar Castillo start at left-back in just his second national team appearance. Heath Pearce is also a good potential option to try there.

Shea and Beasley: The old and new

DaMarcus Beasley sounded surprised about his first call-up in almost a year and a half, but the fact is the U.S. pool lacks many quality left-footed options, so he'll get another long look from Klinsmann.

Shea didn't do much his first time around with the national team, but as one of the hottest players in MLS, Shea has earned the chance for another lengthy look and Wednesday could be his chance to show his form for FC Dallas is a sign of a player ready for a bigger role, both with the U.S. Olympic Team in 2012 and eventually the senior team for 2014.

The Mexican influence

Edgar Castillo and Jose Francisco Torres have long had vociferous backers who believed they could both excel with the U.S. and when both were called up along with Michael Orozco, it became clear that Klinsmann was eager to get a good look at three Mexican-American players who had held their own in Mexico.

Orozco seems like the biggest wild card of the bunch, having failed to impress that much during his stint in MLS with the Philadelphia Union, but he's done enough to catch Klinsmann's eye.

Torres is an intriguing option for Klinsmann. He's match fit playing in the Mexican season with Pachuca and could be an option to start against Mexico ahead of Michael Bradley, who's currently looking for a new club.

As for Castillo, it remains to be seen whether he's a better fullback option or a greater threat as a winger. We'll get our first look at where Klinsmann prefers him on Wednesday.

Michael Bradley's response

Everyone is waiting to see how Bradley will react in the wake of his father's firing as U.S. head coach. If his responses in Tuesday interviews are any indication, the veteran midfielder isn't about to let his father's departure affect his game. If anything, it could serve to motivate him, as it did in 2005 when Bob Bradley was fired by the MetroStars late in the season. Bradley responded with a strong of good performances, capped by a playoff berth-clinching goal in the regular season finale.

Freddy Adu is likely to get the chance to impress Klinsmann. (Gabriel Bouys/Getty Images)

Building on Adu's Gold Cup

One of the biggest bright spots from the Gold Cup was Freddy Adu's two impressive performances, and the fact that Klinsmann has called in a player who has yet to resolve his club situation indicates that the coach liked what he saw.

Not being in pre-season with a team could impact Adu's sharpness and keep him from a bigger role on Wednesday, but don't be surprised if we see more glimpses of magic from him, and more appearances by him under Klinsmann in the coming months.