Towering Isner emerges as America's hope for Flushing Meadows CINCINNATI (Reuters) - Long before Andy Roddick retired at the U.S. Open last year American tennis had been searching for someone to wave the Stars and Stripes at Flushing Meadows. That man has stepped forward this summer with towering John Isner and his booming serve looking ready to make some noise when the final grand slam of the season gets underway on August 26. Roddick exited the sport to great fanfare last September taking his final bow on the same Arthur Ashe Stadium court where he had claimed his one and only grand slam title. This year it will be a full decade since Roddick became to the last American man to hoist the trophy and the search continues in earnest for the next in an illustrious line of homegrown winners that also includes, Pete Sampras, Andre Agassi, John McEnroe and Jimmy Connors. The search has been tough -- last week's world rankings did not include a single American in the top 20 for the first time since the classification began in 1973. That changes on Monday though when Isner will move from 22 to 14 in the world and he underlined his U.S. Open ambition forcing world number two Spaniard Rafa Nadal to grind out a 7-6 7-6 win in the final of the Western and Southern Open on Sunday. While it is far too early to put Isner's name in the same sentence with any of the greats of American tennis the 27-year-old is looming as the big dangerman in Flushing Meadows. His game is on the rise. He's improving a lot, and he's moving fast," said Argentine Juan Martin Del Potro, the 2009 U.S. Open winner. His serves are unbelievable, and nobody wants to play against him. Since retiring in the second round at Wimbledon with a left knee injury Isner has been in brilliant hardcourt form putting together a 16-4 match record while picking up his seventh career title in Atlanta followed by runnerup finishes in Washington and Cincinnati. Along the way to Sunday's final Isner knocked off three top 10's, world number one Novak Djokovic, number seven Del Potro and number 10 Milos Raonic. "Nobody likes to play against a great player, and nobody likes to play against a player who you will not have the chance to be on rhythm for most of the time," said Nadal. John is this kind of player that, in my opinion, he should be fighting for the Masters, for the top 10. Of course, with his serve, advantage is huge. So if he's playing well mentally and he's making the right decisions in important moments, he's a player that it's very difficult to stop. Certainly, if nothing else, Isner has raised expectations heading into the U.S. Open but remains reluctant to shoulder the added burden of being the next great American hope leaving that duty to four-time U.S. Open champion Serena Williams. "I never felt like I was a guy who was going to carry American tennis at all," said Isner. The fact that I ever even made it to the top ranked American is a huge surprise for me, and I feel very proud that I can say that. I'm just worried about myself and trying to play this sport as long as I can, because I realize I'm in a very fortunate position to do what I do. So I want to do it as long as possible. The towering 6-foot, 10-inch (2.08m) Isner is the perfect fit for the largest stadium in tennis, the big American thriving on home turf. Isner has traditionally saved his best for the home crowd with 14 of the his 16 career ATP Tour final appearances coming in the U.S. and can expect a massive lift from a raucous stadium that will be squarely in his corner. "I'm just comfortable in the U.S. It's something I need to improve on," said Isner. Really sort of saved my season the last four years every time the summer rolls around in the States. I'm probably always going to play my best tennis in the States but I can always improve over in Europe. One thing is these are surfaces I'm comfortable on, but also the support that I have from the fans and whatnot, it helps a lot. What it all comes down to is me being comfortable. I think that's the main key. Writing by Steve Keating in Cincinnati, editing by Simon Evans in Miami.