Belinda Bencic, of Switzerland, celebrates after defeating Donna Vekic, of Croatia to reach the semi-finals of the US Open. Photo: Sarah Stier/AP Photo

NEW YORK  Belinda Bencic kept the Swiss flag flying at the US Open on Wednesday when she reached her maiden grand slam semi-final, winning 7-6 (7-5), 6-3, against Donna Vekic.

The 12th-seeded Bencic fought from a break down at 6-5 in the first set, before winning the tiebreak and taking the last four games against tournament number 23 Vekic, wrapping up matters on a third match point when the Croatian hit a forehand wide.

Her victory came after fellow Swiss players Roger Federer and Stan Wawrinka went out in the men's quarter-finals the previous day. Bencic had reached the quarters by beating Naomi Osaka, her fourth win in five meetings with number one ranked players.

"I just really like the challenge. For me the big courts is a big motivation. I dreamed of this as a kid," the 22-year-old Bencic said.

In the semis Thursday, Bencic faces either in-form Canadian teenager Bianca Andreescu or Belgium's Elise Mertens, who has yet to drop a set at Flushing Meadows.

Set for later Wednesday are also the remaining two men's quarter-finals: Three-time champion Rafael Nadal faces Diego Schwartzman and 13th seed Gael Monfils plays number 24 seed Matteo Berrettini.