To hear Frances Tiafoe tell it, Taylor Fritz predicted this sort of moment for the two of them. It was during an early morning plane ride together a few years ago that the conversation turned to the future and possibilities, Tiafoe recounted after setting up a U.S. Open semifinal on Friday against Fritz, another 26-year-old American, that guarantees the United States will have a man in a Grand Slam title match for the first time since Andy Roddick lost to Roger Federer at Wimbledon in 2009.