Roddick calmed considerably by the time he met reporters, perhaps as part of his Twitter promise to maintain his composure after an embarrassing meltdown in Mason, Ohio. There, he smashed his racket, smacked a ball into the stands and argued with the chair umpire. “Won’t go mental,” he wrote. “Book it.”  The problem, though, was not so much that Roddick lost his cool, but why he lost it. In recent weeks, he spoke of the abdominal injury that sidelined him from even practice until two days before that tournament, of his mounting frustration. He said he last played his “best tennis” in April. Not April, earlier this year. The April before that.  For a decade, Roddick was the best hope for American men here, and since 2003, he was always seeded ninth or higher. But that landscape is shifting. On Wednesday, the Americans John Isner (seeded 28th), Robby Ginepri, Alex Bogomolov Jr. and Jack Sock won first-round matches, and Mardy Fish, who has succeeded Roddick as the top American, is set for second-round play on Thursday.  Roddick, meanwhile, must increasingly rely on guile, competitiveness and his always exceptional serve. He used all three at times against Russell, attacking the net, cutting off angles, even earning his first service break with a backhand winner down the line, a shot hit while skidding across the court.  These were some of the subtle changes Patrick McEnroe, general manager of player development for the United States Tennis Association, suggested Roddick needed to implement, effective immediately. Roddick, McEnroe said, needs to position better, to hit the ball earlier and finish points more quickly. To continue to boom serves and play defensively from the baseline would only distance him from the elite, McEnroe reasoned.  “There’s a difference between what he’s done and where he is,” McEnroe said. “I’ve been imploring him to change the way he’s playing. I don’t believe he’s done that.”  Other Americans have moved in the opposite direction. One is Fish, who shed 30 pounds and entered this tournament seeded eighth. Another is Isner, who secured his 18th win in his last 22 matches Wednesday, outlasting Marcos Baghdatis of Cyprus in four sets. Isner seems primed for a deep run.  Beyond the more obvious Americans, there was Sock, the two-time reigning U.S.T.A. Boys’ 18s national champion, who toppled the Frenchman Marc Gicquel, 6-4, 6-3, 1-6, 6-4, and said of the Open atmosphere, “it’s sweet.” His story sounds much like Roddick’s — Nebraska roots, success in juniors. Fittingly, the two will meet in the second round.  There was Bogomolov, a 28-year-old who once washed out of professional tennis and landed in Long Island as a teaching pro. Between 2003 and 2008, he floated between No. 97 and No. 220 in the world. He injured his left wrist and needed surgery. He decided if he could no longer win, he would teach. But the game called him to return, the same way it calls Roddick to hold on.  Andy Roddick has played in many prime time matches before, but this year he is not the focus of the American men.  Bogomolov bested Steve Johnson, his sometimes doubles partner, to advance to the second round. “I got into the top 100 when I was younger, but I didn’t feel like I knew what I was doing at the time,” Bogomolov said. “I sort of got lucky.”  Equally surprising, on the women’s side of the draw, was Christina McHale, another American and basically a local, from Englewood Cliffs, N.J. She did not consider herself lucky. She considers herself good. McHale knocked out Marion Bartoli, the eighth seed, in the second round, 7-6 (2), 6-2, then calmly lifted her arms in celebration. The 21-year-old Irina Falconi, who had not won a match in four Grand Slam appearances before her first-round win here, followed with a 2-6, 6-3, 7-5 upset victory over 14th-seeded Dominika Cibulkova.  In the final night match, Maria Sharapova of Russia, the third seed, overpowered Anastasiya Yakimova of Belarus, 6-1, 6-1. After she nearly lost Monday, Sharapova moved easily into the third round.  Against Russell, Roddick slowed, battered by mental errors and forehand winners, and lost the third set. He would rally, hold on, and advance, but is far removed from his form in Opens past. “I’m not going to sit here and pretend I’m in championship form right now,” he said.  McEnroe said: “I believe he can still do it. But I believe time is running out. I want to see him go out with a bang.”  This tournament, of course, would suffice, for McEnroe, for Roddick and for the fans here who have adopted him. All involved, even tennis analysts, hope his strange summer continues well into next week.  A version of this article appears in print on September 1, 2011, on Page B17 of the New York edition with the headline: Roddick Is Able to Forge Ahead as Younger Americans Start to Rise. Order Reprints| Today's Paper|Subscribe
Needing nearly three hours and four sets to advance, Roddick’s shine is fading, while other American men are rising.