Andy Roddick, who — you may have heard — announced his retirement earlier this week, effective when his shelf life expires at this year’s US Open, has been the face of American men’s tennis for the better part of a decade. Imagining a post-Roddick landscape, I’m guessing many casual fans, and perhaps even a few seasoned analysts, immediately scrambled to survey the grounds of the Billie Jean King National Tennis Center and paged through their US Open programs to determine who might be anxiously waiting in the wings to fill Roddick’s void.

Is it too soon to try to annoint a successor to Roddick, especially since he’s still going strong in the tournament? Well, sure. Is it fair to take a look around and see who’s coming down the pike? Why not?

Pete Sampras rocketed onto the scene by snatching his first US Open title at 19. Roddick himself won his first and only major here at the age of 21. The desire to identify a young talent ready to catapult to the top of the heap is natural, though of course the danger is that the hype machine can put unfair pressure on young shoulders — even if they’re as broad as those of one of those hopefuls, 19-year-old Jack Sock.

Several of Andy Roddick’s contemporaries are still playing, of course. But Mardy Fish, a former top-tenner who’s now ranked 25, and James Blake, are both veterans in their 30s whose best tennis is likely behind them. A once-future hopeful, Donald Young, has faded fast after his best-ever result at last year’s Open, on his way to plummeting out of the Top 100 and back to the Challenger circuit. Young seems like a veteran who’s been through the ringer, even though he’s only 23 years old.

The most likely successor, of course, is Big John Isner, who’s cracked the top 10 but remains best known for his Wimbledon war of attrition (70-68 in the fifth set v. Mahut). Isner is the rare college graduate in professional tennis, and because it’s taken him a while to grow into his 6-foot-9 frame and fill out his game around his towering serve, he’s already 27 — just three years younger than Roddick — and yet to reach a Grand Slam semifinal. Could Isner win a major? Possibly, though in the era of Federer, Nadal and Djokovic (and Murray and del Potro), it’s a tall order.

Another tall American, 6-foot-6, 24-year-old Sam Querrey, has labored around the edges of the top echelons, but seems to have plateaued as a top-20ish player. Brian Baker may be a new name to many, and in a manner of speaking, he is in fact a new contender in the pro ranks: The talented 27-year-old suffered through several lost years due to a myriad of injuries and surgeries.

If those relative veterans aren't exactly candidates for the long haul, who are the real youngsters, the ones whose games may still be a bit immature, but who have begun to demonstrate the kind of potential that might take them to the top of the American game? Seven American men made it through to the first Saturday--more than any year since 1996--but predictably, entering the second week at the Open, it's Roddick who's the last man standing. The following are the top contenders to claim the spotlight, but it's far from clear that there's a true world beater among them.

Jack Sock. It would be difficult to write a TV character more quintessially American than Jack Sock. This beefy heartlander (just like Roddick, born in Nebraska) has a baby face, backwards baseball cap, red, white and blue tennis togs and a firecracker of a serve. His name even provokes cheesy American outcries, like “Sock it to him, Jack!” Sock pulled off an upset of the 22^nd seed Florian Mayer in the first round, and then extended No. 11 Nicolas Almagro to the limit before succumbing after three tiebreaks, falling just short of reaching the fourth round at his second US Open. Sock’s game is still raw and immature, though; while he is capable of crushing spectacular winners with his forehand, he is almost as liable to hit overeager, boneheaded shots from out of position. He seems to enjoy the stage and attention, and tends toward bold rather than timid shots on big points. In addition to harnessing his game, Sock will need to improve his fitness and mobility, and transform his backhand into more of a weapon, but the raw material is there.

Ryan Harrison. The 20-year-old Harrison lives only a couple miles away from his his mentor Roddick in Austin, TX. Perhaps he’s hoping for some Hill Country osmosis that will help him transition from top-prospect junior to top pro. Harrison has climbed to Np. 61 in the world, and while he’s got a solid game, some questions remain as to whether he can develop the big weapon — and temperament — to go a whole lot higher. He has yet to make it past the second round in a major. Against former US Open champion Juan Martin del Potro on Friday, Harrison made a run, but for much of the match was outclassed by the Argentine.

Steve Johnson. In the global game that tennis has become — its tournament draws flush with exotic surnames — the moniker Steve Johnson probably doesn’t call too much attention to its owner. But Johnson, a two-time NCAA singles champ (undefeated in his final two years of college ball at USC) who’s ranked 245, was granted a wildcard entry to the US Open. He promptly won his opening match and then upset  the wildly talented head case, Ernst Gulbis of Latvia, who had earlier beaten the surprisingly, streaking veteran Tommy Haas. Johnson also teamed with Sock to register one of the tournament’s biggest, if least talked about, first-round upsets, knocking off the top-ranked team of Max Mirnyi and Daniel Nestor in men’s doubles. The 22-year-old Johnson is learning to make the difficult transition from dominating college tennis to being an also-ran (thus far) in the pro ranks. He’s got (all-court) game, up against the major if quixotic talent of the artistic Frenchman and 13^th seed Richard Gasquet, Johnson was out of his league. Still, the future looks bright for this Southern Californian.

Milos Raonic. If the player roster to this point doesn’t strike you as impressive enough, perhaps we could abandon our parochialism (even in the midst of this season of political conventions) and gently expand our geography. Were we to consider North America instead of only the United States, we’d have a clear leading contender. The Canadian Raonic, just 21, is already up to 16 in the rankings (and rising). Raonic’s idol as a teen was Pete Sampras, and the Canadian modeled his massive serve (clocked in the 140-mph range) after the 14-time Grand Slam winner. Many observers, including John McEnroe, consider the 6-foot-5 Raonic the youngster with the greatest potential to step up and become the great (North) American hope. He demonstrated his prowess by thoroughly spanking the veteran Blake, 6-3, 6-0, 7-6 (3) to reach the fourth round.

• Milos Raonic Bio
• Steve Johnson Bio
• Christian Harrison Bio
• Jack Sock Bio