NEW YORK - Roddick announced last week that this U.S. Open would signal the end of his long career. Having prolonged the final farewell by winning three straight matches, Roddick, the best tennis player the United States has produced since Pete Sampras and Andre Agassi, finally ran out of steam against Argentina’s Juan Martin del Potro in Round 4.Even before the final ball was struck, Roddick had tears in his eyes, while his wife Brooklyn Decker and his mother Blanche openly wept in the stands, as del Potro moved towards a 6-7, 6-6, 6-2, 6-4 victory."It has been a road of a lot of ups and downs and great moments,” Roddick said in his courtside interview minutes after the match. "For the first time in my career I’m not sure what to say. Since I was a kid I have been coming here to this tournament and I felt lucky just to be at there in the stands. I have loved every minute of it.”The U.S. Open has seen many great fairytale runs from legends on the brink of retirement, from Jimmy Connors to Sampras and Agassi. Against del Potro, however, Roddick simply came up against an opponent who was younger (del Potro is just 23), fresher and in far better form.Roddick, 30, had come out with all guns blazing on Tuesday night, racing to a 5-2 lead in the opening set before being pegged back to 6-6. Then the rains started to tumble over Flushing Meadows, this tournament plagued by the weather for yet another year.When play resumed Wednesday, Roddick started brilliantly, surging through the tiebreak while losing just a single point as del Potro struggled to shake off the overnight cobwebs.When the second set headed to a tiebreak after a glut of huge serving, Roddick, the No. 20 seed in the tournament to del Potro’s seven, was in real contention. However, the Argentinean held strong to clinch it, and it was one-way traffic from then on.Del Potro broke Roddick’s serve in the first game of the third set, then streaked clear to win it 6-2. The fourth was a similar story. Roddick lost his serve in the fifth game and the end was approaching. Even though Roddick staved off one match point in the ninth game, del Potro comfortably served out the match to love."He was just too good,” Roddick said. "He is one heck of a player and he has as good a chance as anybody here.”Friday marked exactly nine years since Roddick celebrated the finest moment of his career, when he brushed aside Juan Carlos Ferrero to win the 2003 U.S. Open in what looked certain to be the first of many majors.As he strode up into the stands, kissed his then-girlfriend Mandy Moore and contemplated his new-found status as world No.1, he could not have imagined that he would never again scale to those heights.But then along came Roger Federer to dominate the sport like no one before him, with Rafael Nadal and eventually Novak Djokovic emerging as the only other men capable of regularly challenging for major silverware.Aside from those three, del Potro, the 2009 U.S. Open champion, is the only other player to have lifted a Grand Slam trophy since Roddick’s triumph in ‘03.The American continued to be competitive, reaching three Wimbledon finals and another U.S. Open final, losing to Federer on each occasion. The most memorable, that epic showdown on the London grass in 2009 that saw Roddick lose 16-14 in the fifth set, will always occupy his mind as the one that got away.