AT FIRST GLANCE, DeAndre Yedlin seems like an unlikely choice to have emerged as the United States national team’s super-sub at this World Cup.

After all, we’re talking about a 21-year old with less than a year-and-a-half of professional soccer who could be entering his senior year of college. He made the World Cup team with just two caps to his name, and now he is establishing himself as a defender who is a difference maker on offense.

But making the most of opportunities is something the Seattle Sounders speedster has done most of his young career. And it's a big reason why he’ll likely be one of the first players Juergen Klinsmann turns to this afternoon when the U.S. needs a second half spark against Belgium in the Round of 16 match in Salvador.

“He’s a guy who manages to do things before people expect,” said Portland Timbers coach Caleb Porter, who coached Yedlin for two seasons at the University of Akron. “When he got to college, we thought there’d be a transition time but he showed in preseason he was ready and he started right away… At Seattle, I don’t think even in their most optimistic projections did they see him having the impact he’s had right away but he became a starter almost immediately."

"And now with the national team, he’s making an impact even with his inexperience.”

It raised eyebrows when Klinsmann named Yedlin to the provisional 30-man roster for the World Cup, and when the Seattle native survived the cuts to earn one of the 23 plane tickets to Brazil, many thought Yedlin would spend the tournament tethered to the bench, soaking up the atmosphere and experience to be applied for future national team appearances.

But with the U.S. tied with Portugal and needing a spark, it was Yedlin, usually a right back but playing in midfield, who entered in the 71st minute as the first American sub. Ten minutes later he overlapped down the right flank, catching up to a Jermaine Jones pass and sending in a cross that was eventually trundled in by Clint Dempsey.

Four days later with the U.S. down a goal against Germany, Yedlin was inserted in the 84th minute and in the dying moments helped create the Americans’ two best scoring chances. In the 93rd minute Yedlin collected ball at midfield and streaked down the right flank and sent in a low cross that culminated in a promising shot by Alejandro Bedoya that was blocked by a desperation save by Phillip Lahm. Seconds later Yedlin again flashed his athleticism, leaping to get his head on the end of a cross and nodding it to Dempsey, whose header went just over the crossbar.

“I think the role Jurgen is using him in is perfect for where he is right now,” said former MLS player Darren Sawatzky, who coached Yedlin since he was 12, first with Washington’s ODP program then the Sounders academy and later the Sounders PDL team. “They are playing to his strengths, let him come in against tired opponents and use that speed to create danger.”

That speed is what has helped Yedlin’s meteoric rise.

“It’s world-class,” Porter said. “You hear that term a lot but there aren’t very many players out there with his speed.”

Yedlin isn’t close to a finished product. “I think the player he is right now isn’t close to what he’s going to become,” said Sawatzky. “He’s just beginning to scratch the surface.”

Yedlin was timed in the 40-yard dash at Akron and “was running about a 4.2 or 4.3,” said Jared Embick, who replaced Porter as Akron’s head coach. “People talk about NFL guys running 4.2, 4.3. DeAndre has that kind of pace. But it’s not just that he’s fast, he’s strong, he runs strong, and that makes him able to run through contact, fight off tackles.”

Like most elite youth players, Yedlin was an attacking player for most of his club soccer days. Porter spotted him when he was assisting at a U.S. Under-18 national team camp and afterward sent Embick to recruit him. After Yedlin committed to Akron he was converted to right back to best utilize his pace and strength.

“He’s got the perfect skill-set for the modern game outside defender—bombing forward into the attack,” said Sawatzky. “Obviously he’s got the athleticism but also the skill. But he’s still learning to defend. He’s only been playing right back since 12th grade and for him that’s just four years ago. So his 1-v-1 defending will only get better the longer he plays.”

His defensive shortcomings were why Tab Ramos didn’t include Yedlin on last year’s U-20 national team roster for the CONCACAF qualifying tournament for the U-20 World Cup. That turned out to be a blessing in disguise as it allowed the rookie Yedlin, who signed a Homegrown contract with the Sounders after his sophomore year, to spend preseason with his new club and show Sigi Schmid and his staff he could compete in MLS.

“I give Sigi a lot of credit for his development,” said Porter, aware of the trouble he could find himself with Timbers Army for complimenting his team’s biggest rival. “It’s hard, in MLS, to develop young players when you’re expected to also win games. But Sigi gave (Yedlin) a chance and believed in him and let him to play to his strengths while he developed the other parts of his game that needed, and still need, work.”

Other than his speed, what’s most immediately noticeable about Yedlin are a series of hair-do’s best described as colorful. They are so unusual that twice they have caught the attention of NBC’s Jimmy Fallon, who has described him as looking like pop diva Rihanna.

“People see the hair and they think he’s this flashy guy,” Embick said of Yedlin, who was raised by his grandparents. “But honestly, that’s the only thing really ‘out there’ about him. “He’s a really quiet and down-to-earth kid who is all about his team and his family and friends.”

For the World Cup, Yedlin has toned down the hair, relatively speaking. But the speed is still there, of course, and if the U.S. is in need of a jump-start against Belgium, Yedlin and his wheels will likely be called upon to make an impact.

Brooke Tunstall is a veteran journalist who has covered Major League Soccer since its initial player dispersal draft. Follow him on Twitter.