Shawn Johnson, Bianca Flohr and Samantha Peszek lead the field at the American Cup, an international competition that begins today in Jacksonville, Fla. The trio dominated the junior ranks in the United States and internationally, and this weekend will be their first test at the senior level. Bieger was supposed to compete this weekend, but she had to withdraw after getting hurt in training on Wednesday night. “This is a normal situation,” said Martha Karolyi, coordinator of the U.S. women’s team. “The generation coming up has to be stronger than the generation before to achieve the progress that is absolutely necessary.” Though the Americans don’t return anyone from the team that won silver at the Athens Olympics in 2004, this isn’t a typical rebuilding effort. If anything, the U.S. team in Beijing could be even stronger. In addition to finishing second in the all-around, Bieger won a silver on vault at the world championships. Memmel has six world medals in her collection, three of them gold, and was the first U.S. woman since 1994 to win the all-around at worlds when she edged Liukin in 2005. Liukin’s six world medals include golds on the balance beam and uneven bars. There’s also Alicia Sacramone, one of the sport’s best vaulters and owner of four medals from the last two world championships. Make way for the next generation of U.S. gymnasts. It was only a few years ago that Chellsie Memmel, Nastia Liukin and Jana Bieger were “up-and-comers.” Now they’re grizzled veterans, and there’s a whole new crop of youngsters eager to show what they can do – starting this weekend. The Americans were upset by China at the worlds, but both Memmel and Liukin were battling injuries. Add the juniors to the mix, and the competition for the six spots in Beijing could be tight. “Everybody starts with a blank slate at the beginning of the year. We’re all working to do better than we did last year,” said Johnson, a perky 15-year- old nicknamed “Peanut.” “Everybody thinks about the Olympics, but you only try to think about what’s next and not what’s in the future.” 160Want local news?Sign up for the Localist and stay informed Something went wrong. Please try again.subscribeCongratulations! You’re all set!