Before he immigrated to the United States, Don Ahn loved playing tennis in his youth in South Korea. He wanted his children to play, too.

Getting his daughter, Kristie, to take up the sport was easy. Getting her to stop is proving far tougher.

Kristie Ahn, 27, was born at Flushing Hospital, just two miles from the Grandstand court where she defeated Jelena Ostapenko on Saturday in third round of the United States Open.

The match was a high point of Ahn’s career. Her three wins this week were her first in the main draw at a Grand Slam tournament — 11 years after her first try. Her parents had hoped her perseverance in tennis would have worn off by now.