No doubt about it: heading into 2013, opportunities in the U.S. national team’s defense are wide open. There are two major reasons for this reality.

The first is that no American player truly owns his position on the U.S. back line. Steve Cherundolo, the veteran right back, is the player with the strongest hold on his position, but his age—33—could still be an issue in World Cup Qualifying. Aside from Cherundolo, Carlos Bocanegra, also 33, is beginning to show his age.

On the other end, Geoff Cameron has played well over the past six months, but he still hasn’t solidified himself in the lineup—and his need to transition from right back with his club, Stoke City, to center back for the U.S. can still prove to be a challenge for him. Fabian Johnson looks to be the best candidate for left back, but like Cameron, his emergence is recent. Michael Parkhurst still looks like a back-up for Cherundolo or Johnson, and the same goes for Clarence Goodson in the middle of the back line.

The second reason is that in 2013, the U.S. national team will flat-out need a large pool of players. After the United States’ 1-0 victory over Guatemala on October 16th, Jurgen Klinsmann said: “2013 …will be extremely, extremely busy for us. We’re gonna play friendlies, World Cup Qualifiers, and a Gold Cup, so we have to build two rosters for that. Because we can’t have players do both. We have players now coming also through MLS. They are knocking at the door, they are getting stronger in MLS.”

The MLS playoffs are upon us and a handful of young American defenders have a great opportunity to prove their value to their club—and maybe earn a spot in January’s national team camp. In the playoffs, they’ll face the league’s best attackers and play with their season on the line. Under that type of pressure, we’ll see if they can step up, shut down opposing attackers, contribute to their team’s offense, and help lead their clubs to victory.

Here are the top five young American defenders in the MLS playoffs fighting to get a shot at the national team.

Omar Gonzalez (ASN Rank No. 22)—Every conversation I have with analysts and writers about prospects for the American back line begins (and often ends) with Omar Gonzalez. The 24-year-old 2011 MLS Defender of the Year has a single cap to his name. A torn ACL, suffered in his first day of training with Nuremberg in Germany last winter, kept him out of the national team all year and the Galaxy lineup through July. Of all the young American defenders in the MLS playoffs, his job is the hardest: in L.A.’s Western Conference Semifinal Series against San Jose, he needs to control Chris Wondolowski, Steven Lenhart, Alan Gordon, and the rest of the Earthquakes offense, which led the league in scoring with 72 goals.

On Sunday night, he was up to the task for 90 minutes. He won the battle with Lenhart, shutting down the combative striker, and he helped Tommy Meyer mark Wondolowski, holding the league’s most dangerous scorer to only two half-decent chances on goal. But in extra time, Gonzalez made a terrible error: standing in the wall, he let a weak 30-yard free-kick by San Jose center back Victor Bernardez past his leg, through the wall, and toward the Galaxy goal. Galaxy goalkeeper Josh Saunders let the ball slip under his body and into the net. San Jose escaped with a crucial 1-0 victory, a win that puts all the pressure on L.A. in the series’ second leg in San Jose on Wednesday.

In the Galaxy’s MLS Cup run last season, Gonzalez proved his poise, ability, and championship pedigree. But if he intends to be a prospect for the national team heading into World Cup Qualifying, he’ll need to play with more consistency against the league's best offense.

Heath Pearce (ASN Rank No. 45)—Of all the American defenders in the MLS playoffs with a shot at getting a call-up to the national team, the 28-year-old Pearce has the most international experience. That said, many of the New York Red Bull left back's 35 U.S. caps came under Bob Bradley prior to the 2010 World Cup. Pearce was included in the January 2012 national team camp, and a solid playoff performance this year could find him in the annual January camp again.

One thing working in Pearce’s favor is his position. Aside from Fabian Johnson, no American has shown himself a strong candidate for the left back role. In New York’s series against D.C. United, Pearce is tasked with shutting down Chris Pontius and the rest of the D.C. attack. The defender earned a bit of good fortune when United Andy Najar was red-carded in Saturday’s match. D.C.’s right back was a dangerous threat up the right flank all season. Without needing to worry about Najar’s offensive forays, Pearce may be able to commit to some of his own.

Matt Besler (ASN Rank No. 46)—Klinsmann included the 25-year-old Sporting Kansas City center back in the squad that went down to Mexico City in August and earned the United States’ historic 1-0 victory. But Besler didn’t see the field in that match, and he still has yet to register an appearance for the national team. In SKC’s series against Houston, Besler’s job is to contain Will Bruin, Ricardo Clark, and Calen Carr.

He got off to a rough start. In the 18th minute of Sunday’s match, Houston’s Adam Moffat scored a screamer from outside the penalty area to give the Dynamo a 1-0 lead. Then, in the 75th minute, Besler got caught out of position and failed to close down Carr, who played a ball across the penalty box to Bruin. The result was an important second goal.

Besler has a chance to redeem himself on Wednesday, when the second leg of the series is played at Livestrong Sporting Park in Kansas City. And the pressure will surely be on him and the rest of the Sporting back line: SKC will need to attack with abandon to make-up their two-goal deficit, which could leave Besler and fellow center back Aurelien Collin exposed. If Besler can shut down Bruin, Carr, and Clark while holding down the back, he might show that he’s got what it takes for the next level.

Steven Beitashour (ASN Rank No. 65)—Along with Besler, Klinsmann included Beitashour, the San Jose right back, in the U.S. squad for the August 15th match against Mexico. Like Besler, Beitashour still has zero caps with the national team. But with San Jose’s appearance in the playoffs, Beitashour has the chance to shine. Against L.A. his primary duties are trying to contain Mike Magee, who often plays left midfield for Galaxy, and the occasional forward forays of Galaxy left back Todd Dunivant. Along with those defensive duties, his next key objective is to push forward—as he likes to do—and provide an attacking spark by finding open space on the flank and sending in dangerous crosses. That opportunity could prove him in good stead with Klinsmann, who wants to see his outside backs push high and be integral parts of the attack.

San Jose held a line well against the Galaxy on Sunday and escaped with a 1-0 win. If they win the series and continue their march to the MLS Cup, Beitashour’s performance might earn him an invitation to January’s camp, particularly if he makes a crucial offensive contribution in one of the playoff games.

Tony Beltran (ASN Rank No. 100)—Beltran has yet to be included in a national team camp, but the 25-year-old defender could see that change if he can help Real Salt Lake get past the Seattle Sounders in the Western Conference Semifinals. Beltran, a right back, needs to contain Seattle’s right midfielder Brad Evans and provide support in covering Fredy Montero, Samual Ochoa and, if he plays, Eddie Johnson. But since Beltran is an outside back, he’ll need to make a difference on offense, too. If he can own the right flank against Seattle, he may get his first call-up to the national team.

Andrew Lewellen (@AndyHLew), a former college soccer player and youth coach, is now a freelance writer based in Los Angeles. Read more of his soccer writing on his blog, Andy’s Pitch.