The breakout performance in the men's draw has been turned in by 24-year-old John Isner, who turned pro in 2007. With a big serve, consistent groundstrokes and high-risk, high-reward strategy, Isner is quickly advancing through the ranks. Showing no residual effects from the case of mononucleosis that forced him to miss both the French Open and Wimbledon this year, Isner has momentum from strong summer results and is peaking at the U.S. Open.

While his 38 aces and 90 total winners in a five-set victory over No. 5 Roddick were impressive, what stood out even more was his ability to beat the top-ranked American in a fifth-set tiebreak. Isner took the game out of Roddick's hands, raised the level of his play and convincingly earned a spot in the fourth round.

As Isner continues to improve his fitness and movement on the court, there's no doubt that he can continue to advance in the rankings and consistently find himself deep in tournaments. You can’t teach height, and Isner’s 6-foot-9 frame makes him a tall order to defeat.

He and U.S. Open doubles partner Sam Querrey are the rising men’s stars behind Roddick. After admiring Andy and aspiring to his level of success, both John and Sam are at the point in their careers where they need to make that a reality. Isner and Querrey have shown they have the talent to be top-15 players and have had big wins over top Tour players. Now they need to string together those wins and follow Roddick’s example by getting more physically fit.

Even though 26-year-old Jesse Witten bowed out in the third round, the U.S. Open did remarkable things for his flagging tennis prospects. Dropped by his only sponsor earlier in the year and bouncing around small challenger events, Witten was contemplating retirement. One week at the U.S. Open recharged his career.

He soundly defeated No. 29 Igor Andreev in the first round and nearly knocked off No. 4 Novak Djokovic before falling in four tightly-contested sets in the third round. Those performances should demonstrate that he has a future in professional tennis and motivate him to get into the best shape of his life. Hopefully, this will give him the confidence and the spark to continue on.

Slideshow   Back in New York Look back at all the action from the 2009 U.S. Open. NBCSports.com

The hard part is that he's still not ranked and will head off to another small tournament next weekend. Witten will need to find the same motivation in front of the one hundred or two hundred fans there that he did in front of large and loud crowds in New York. 

One American that few expected to make an impact in this year’s draw is Taylor Dent. Bedridden for weeks after back surgery in 2007 and out of tennis for over two years, he has taken his serve-and-volley game to the third round at the U.S. Open. His utter joy at being back on a big stage has been contagious. The reaction of the crowd after his five-set, second-round victory over Ivan Navarro was one of the highlights of the tournament thus far.

Even though he faces a tough challenge against No. 2 Andy Murray in the third round, Dent’s performance has erased many question marks about his ability to mount an effective comeback.

The success of the younger American players should have a trickle-down effect to junior players across the United States. When they see someone like Oudin knock off some of the Tour's best players, it is bound to give them confidence about their own chances. The word Oudin has printed on her signature sneakers, “Believe,” could become the mantra for a whole generation of American tennis youth.

Also on NBCSports.com Posnanski: Emrick still rises above the rest What does retirement hold for Beckham? Oxbow ruins Orb's Triple Crown bid at Preakness Follow us on twitter: @NBCSports  |  Facebook