Todd Pletcher's two-year-old was the essence of bravery for Napravnik as he looked beaten four furlongs home, having fiercely chased the trailblazing Title Contender from the outset.
Shanghai Bobby suddenly rallied once pressed by He's Had Enough, however, and courageously held off the Paul Reddam-owned grey for a noteworthy success.
Napravnik said: "I hope everybody appreciated the excitement.
"Bobby came to a walk and was looking around and looking at the stands - really unfocussed.
"Once he gets the lead he kind of gets a little lost.
"I knew he was better than that at the four-pole.
"I knew he'd kick back in."
Pletcher said: "I thought we were in big trouble, but it was a courageous effort."
Shanghai Bobby is half-owned by Coolmore, who announced earlier in the week they had taken a 50% interest in the Harlan's Holiday colt.
Daily Racing News
Breeders' Cup Results: Shanghai Bobby on top in Juvenile
"Shanghai Bobby is half-owned by Coolmore, who announced earlier in the week they had taken a 50% interest in the Harlan's Holiday colt."
Rosie Napravnik became just the second woman to win a Breeders' Cup race when Shanghai Bobby dramatically preserved his unbeaten record in the Grey Goose-sponsored Juvenile at Santa Anita.