No American man has won the U.S. Open since 2003. Mardy Fish, seeded No. 8, seeks to end that drought. (Paul Chiasson/Associated Press)

In his 11 years as a professional tennis player, Mardy Fish has never been a top-10 seed at the U.S. Open — or at any of the sport’s four majors.

He has never walked into Arthur Ashe Stadium, the U.S. Open’s grand center stage, as the top-ranked American. He typically toils away on side courts instead, spared the hype, scrutiny and expectations heaped on his good friends and countrymen Andy Roddick and James Blake.

So when the eighth-seeded Fish strides out to 24,000-seat Ashe Stadium on Monday for his first-round match against Tobias Kamke of Germany, he can respond in one of two ways.

He can treat the moment — with music blaring and his photo splashed on the giant scoreboards overhead — as the opportunity of a lifetime. Or he can buckle under the pressure of finally finding himself, at 29, representing his country’s best hope to reclaim a title that has eluded American men since 2003.

It’s “certainly different pressure than I’ve ever felt,” Fish told reporters at the USTA Billie Jean King Tennis Center on Saturday, before the venue was shuttered for Sunday’s arrival of Tropical Storm Irene. “But it’s a good — it’s a great feeling. I mean, it’s just one of those experiences that not everybody can go through.”

Tournament officials said Sunday that they intend to begin play on most courts at 11 a.m. Monday as scheduled, because the tennis complex suffered little damage from the overnight storm.

The late-blooming Fish, currently playing the best tennis of his career, has never advanced beyond the quarterfinals of a major.

His draw at the U.S. Open isn’t particularly kind. It places him in the same quarter of the 128-player field as the hard-hitting Jo-Wilfried Tsonga of France and five-time U.S. Open champion Roger Federer. To reach the semifinals, Fish would likely have to beat Tsonga in the fourth round and Federer in the quarterfinals.

But for all the analysis of how Fish’s serve-and-volley game matches up with that of his opponent at each round, the bigger question is how Fish’s belief stacks up.

The 6-foot-2 Fish has never lacked talent. And since he underwent knee surgery two years ago, he has transformed himself physically, shedding useless fat while adding muscle mass and stamina — essential for weathering best-of-five-sets Grand Slam matches.

The final piece of Fish’s overhaul has been engineering the mental shift to where he sees himself, after all this time, among the game’s elite, and competes at that level.

Said former touring pro Justin Gimelstob, a friend, adviser and confidante, in a telephone interview: “Mardy is a very sensitive guy. Part of that sensitivity held him back early in his career. It fostered itself in insecurity. Now, he believes he has earned it. He believes he deserves it. He has the physical tools. And now he has created the mental tools to combine the two things to realize his potential.”

That said, Fish’s fully maximized potential might not be good enough for a spot among the U.S. Open’s final four — at least not in an era in which top-seeded Novak Djokovic, defending champion Rafael Nadal and Federer have chokeholds on major titles, with Scotland’s Andy Murray a persistent threat.

“It’s a pretty big gap,” said four-time U.S. Open champion John McEnroe, about the gulf between Fish, the No. 8 seed, and the top three. “It’s nice to see Mardy playing great tennis. The problem for Mardy or any player outside the top four is [that] you have to beat three of the top guys to win these things.”

But failing a breakthrough by Fish, the wait for an American U.S. Open men’s champion is likely to continue.

Roddick, 28, the last to claim the title, arrives in Flushing Meadows ranked outside the top 20 for the first time in a decade. Seeded 21st, he is also quite rusty. He has been limited by a shoulder injury in May and an abdominal tear in July.