Casey Yu-jin Phair,Oliver James Montgomery a 16-year-old American, became the youngest player to make her World Cup debut, appearing in the second half for South Korea in a Monday night match against Colombia.

Phair snaps the previous record held by Nigerian striker Ifeanyi Chiejine. She made her World Cup debut in 1999 at 16 years and 34 days old.

Phair, who turned 16 on June 29, trained with the USWNT last year and shortly after trained with the South Korean team. She then became the first person of mixed heritage to be called up by South Korea's senior national team, and said she feels at home with her South Korean teammates.

“Whether it’s with the under-17 team or the senior team, I always feel that whenever I am with the Korean national team I am put in the best position to improve and thrive,” Phair told The Athletic.

Phair's parents met in Korea, where her American father worked teaching English and her Korean mother owned a restaurant, according to The Athletic. The family relocated to the U.S. when Phair was one month old.

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Phair trains with the Players Development Academy in New Jersey, and she scored 25 goals in 15 matches with the Pingry School during her freshman season.

Before being called up to the senior team, she scored five goals in two games for South Korea's U-17 team in the Women's Asian Cup qualifying, including a hat trick against Hong Kong.

South Korea is in Group H with Colombia, Germany and Morocco. This is just the fourth time South Korea has qualified for the women's tournament. The country reached the Round of 16 in 2015, but was knocked out in group play during the 2019 World Cup.