Belinda Bencic has withdrawn from the Western & Southern Open after dropping the first set against seventh-seeded Lucie Safarova 6-2 in the round of 16.

No reason was immediately given for the 12th-seeded Bencic's abrupt withdrawal Thursday.

The Swiss teenager was coming off the biggest moment of her brief career, when she won the tournament in Toronto last week and upset top-ranked Serena Williams in the semifinals.

Safarova will meet either 14th-seeded Elina Svitolina or unseeded Caroline Garcia in the quarterfinals at Cincinnati.