If he has an Achilles heel that may keep him from reaching that goal, it may be the potential for soundness issues. His sire Flatter had talent but fell prey to injury after just six starts, and his dam Party Silks never raced. In addition, broodmare sire Touch Gold did not have the best of feet. Nonetheless, as a Belmont Stakes (USA-I) winner -- and at the expense of horses as good as Silver Charm and Free House, at that -- his stamina is beyond question.
The same cannot yet be said for Upstart, though the potential is certainly there with both grandsires being Belmont Stakes winners. Touch Gold has not transmitted as much stamina as might have been expected, as the average winning distance for his progeny is only 7 furlongs. While that is longer than the AWD for the population at large, it is not so much so that Touch Gold can be considered a reliable source of stamina. As for Flatter, while his son Flat Out certainly handled 10 furlongs well, most of his best progeny preferred shorter trips. The presence of Housebuster as the second damsire also isn't reassuring regarding Upstart's potential to stay 10 furlongs.
Speed is certainly present, as Upstart's dam is a half sister to the good sprint filly Josh's Madelyn (by Quiet American), winner of the 2004 Raven Run Stakes (USA-II). The next dam, Intend to Win, is a stakes-placed half sister to 1995 Royal Palm Handicap (USA-IIIT) winner Gone to Win (by Gone West) and juvenile sprint stakes winner Crafty Buzz (by Crafty Prospector). Ultimately, Upstart's ability to get Classic distances may come down to two things: his own innate balance and athleticism, and whether he gets a favorable trip. As with many other Derby prospects, the chances are good that he may find the difference between nine and 10 furlongs daunting.