Rising American teenager Amanda Anisimova has withdrawn from the U.S. Open following the death of her father and longtime coach Konstantin Anisimova, ESPN reported on Monday.

The cause of death was unknown.

Anisimova, 17, has charged up the rankings this season, following her semifinal run at the French Open that included a win over defending champ Simona Halep. She is currently 24th in the world and would have been considered a threat at Flushing Meadows, where she won the 2017 junior championship.

Konstantin and wife Olga moved to the U.S. from Russia in 1998.