Katelynn Espinosa hugged the shiny silver chalice as if it were a treasured American Girl doll. It sat atop a square wooden base with the words, “Kings County Tennis League Davis Cup,” inscribed into the bottom. It may as well have said, “United States Open champion, 2018.”

Katelynn, 8, snatched the prize, which is almost as big as she is, from her older brother and sister one morning last month and carried it nearly the entire way from the tennis courts at the Marcy Houses in Bedford-Stuyvesant, Brooklyn, to her family’s home at another public-housing project, the Sumner Houses, several blocks away.

There, Katelynn and the two siblings — 12-year-old A.J. Mejias and 10-year-old Janelly Mejias — posed for one more picture to top off their day.

The three youngsters had been part of a daylong tennis carnival organized by a local maverick who happened across a dilapidated tennis court eight years ago, saw an opportunity and then made it happen.