Reigning champion Bianca Andreescu of Canada and Ukraine's Elina Svitolina will not be travelling to New York later this month, leaving Serena Williams as the only one of 2019's semi-finalists set to compete.

Ranked eighth in the world, Bencic is also the fifth player in the women's top 10 to opt not to play. 

Australia's world number one Ashleigh Barty and Kiki Bertens of the Netherlands are the other top-10 players to withdraw.

Bencic did not specifically cite coronavirus concerns when announcing on social media that she had "made the difficult decision to skip the US swing in New York", but that has been the primary reason for so many leading players to opt against playing in the second Grand Slam of the year.

While the health situation there is not as severe as it once was, New York City has been one of the cities hit worst during the coronavirus pandemic. 

In excess of 230,000 confirmed cases have been reported in the city, resulting in more than 23,600 deaths.  

The Billie Jean King National Tennis Center - the US Open venue - was even turned into a makeshift hospital at one point.

Other notable withdrawals from the women's draw include China's Wang Qiang and 2017 French Open winner Jelena Ostapenko of Latvia.

Rafael Nadal, Stan Wawrinka, Nick Kyrgios and Gaël Monfils are among the high-profile men's players who will not be in action at Flushing Meadows, while Roger Federer is injured so will also miss the tournament.

The Cincinnati Masters - moved to New York because of the pandemic - is due to begin on August 20 and serve as a warm-up event.

The US Open will then start on August 31.