"I told Larry, `This is your show. I'm here to follow,''' Roddick recalled. "He promptly said, `OK, lose 15 pounds,' and I regretted saying what I said.''
Now Roddick's slimmer and fitter. But better? That question might be answered at the Sony Ericsson Open, where the No. 5-seeded Roddick plays his opening match Friday night against Diego Junqueira of Argentina.
He's off to the best start of his career with a 23-4 record, and he matched his best Australian Open showing when he reached the semifinals before losing to Roger Federer.
"I've been playing well and winning the matches I'm supposed to win,'' Roddick said Thursday. "I think there is some room for improvement. I'm excited about the rest of the way.''
Seeded players had first-round byes and begin matches Friday, with Federer, Novak Djokovic and Ana Ivanovic among those in action. U.S. men went 4-2 Thursday, with John Isner, Sam Querrey, Amer Delic and Bobby Reynolds advancing. Among those eliminated was Jill Craybas, the only American woman to play.
Roddick hired Stefanki after slipping to No. 8, his lowest year-end ranking since 2002. With a new workout regimen he met the coach's goal of shedding 15 pounds, which has allowed him to chase down shots that might have been beyond reach in the past.
Now Roddick will try to chase down top-ranked Rafael Nadal, Federer and Djokovic in the rankings.
"Larry recognized there is a change in the game,'' Roddick said. "It seems like everything is slowing down a little bit as far as surface and balls, and therefore you see a lot more guys dependent upon their running ability and their legs.
"So we're just trying to keep up. It has worked so far, but we're talking about 2 1/2 months. It needs to be proven for a little bit longer than that to consider it an ultimate success.''
The third-ranked Djokovic noticed the difference last week when Roddick beat him 6-2, 6-3 in the quarterfinals at Indian Wells.
"He's playing better. That's a fact,'' Djokovic said. "He's stepping up more in the court, and you just feel the improvement.''
Nadal beat Roddick the next day in the semifinals, winning two close sets.
"It seems like he has more motivation right now than last few years,'' Nadal said. "He's playing well, no?''
The 26-year-old Roddick has gone 5 1/2 years since winning his lone Grand Slam title at the 2003 U.S. Open. Critics say he has failed to make the most of a serve and forehand that rank with the most formidable in tennis. Defenders say he has done well to win one major title despite an inconsistent backhand and poor net game.
Key Biscayne offers one last chance to make a splash before the tour switches to clay, Roddick's worst surface. He has enjoyed several memorable victories on the island, including an upset at age 18 over Pete Sampras in 2001, and a win over Federer last year to end a streak of 11 consecutive losses to his nemesis.
Roddick and Federer could meet next week in the quarterfinals, with Nadal in the other half of the draw.
Roddick won the tournament in 2004, when he lived nearby in Boca Raton. That's the only time he has reached the final in nine tries, but he bristles at the suggestion he has underachieved in the event.
"I won it; it's tough to say I haven't played well,'' he said. "That's kind of a microcosm of my career, I guess. It's just a matter of how you want to grade it.''