The defending champion and four-time Grand Slam winner withdrew from the French Open earlier this year after being fined for not attending a post-match press conference, and revealed that she had faced "long bouts of depression" since her maiden triumph at the US Open in 2018.

She also pulled out of Wimbledon, but began the defence of her title at the Arthur Ashe Stadium with a comfortable 6-4, 6-1 win against Bouzková.

World number two Aryna Sabalenka of Belarus began her search for a first Grand Slam with a victory over three sets against Serbia’s Nina Stojanović, although she had to recover from losing a second set tiebreak to defeat her opponent 6-4, 6-7, 6-0.

Ukraine’s fifth seed Elina Svitolina, a US Open semi-finalist in 2019, comfortably overcame Canada’s Rebecca Marino 6-2, 6-3 in just 63 minutes.

Sloane Stephens of the United States defeated compatriot Madison Keys in a rematch of the 2017 final, which Stephens won for the loss of just three games.

This was a much closer meeting between the close friends who were due to practice together in the run-up to the tournament but scrapped those plans once the draw was released, with Stephens winning by nine points to seven in a final set tiebreak to triumph 6-1, 1-6, 7-6.

Elsewhere in women’s singles first round matches played during the opening day session, last year’s runner-up Victoria Azarenka of Belarus swept aside Tereza Martincová of the Czech Republic 6-4, 6-0.

Women’s eighth seed Barbora Krejčíková of the Czech Republic defeated Astra Sharma of Australia 6-0, 6-4 to book her place in round two.

Ninth seed Garbine Muguruza of Spain was made to battle by Donna Vekić of Croatia, with the two-times Grand Slam champion winning in two tiebreak sets 7-6, 7-6.

Another two-times Grand Slam champion Simona Halep of Romania was also in action, progressing in two tight sets against Italy’s Camila Giorgi 6-4, 7-6.

In perhaps the first day’s most extraordinary match, Halep’s compatriot Ana Bogdan lost to Spain’s Rebeka Masarova in a three-set thriller that lasted three hours and 40 minutes, and saw each set go to a tiebreak.

Masarova came from behind to go through 6-7, 7-6, 7-6.

The top half of the first round draw is scheduled to take place tomorrow, with world number one Ashleigh Barty of Australia looking to build on her victory at Wimbledon as she starts her campaign against the 2010 US Open runner-up Vera Zvonareva of Russia.

Switzerland’s newly crowned Olympic champion Belinda Bencic is set to face Arantxa Rus of The Netherlands, while 2019 US Open winner Bianca Andreescu of Canada is due to go up against Switzerland’s Viktorija Golubic.