Her charge from obscurity to the US Open title as a 150th-ranked qualifier still feels barely credible, even as the 19-year-old returns to Flushing Meadows as reigning champion. It was a story that defied tennis logic, transcended sport and instantly made her one of the most marketable athletes -- male or female -- in the world. The trouble is, the tennis treadmill never stops and while Raducanu has been dealing with the inevitable spin-offs of her unlikely Grand Slam title, her results have been modest.