Number three seed Sofia Kenin could not win a single game as she crashed out of the Italian Open, thrashed by US Open runner-up Victoria Azarenka.
Rafael Nadal, Novak Djokovic, Simona Halep and Karolína Plíšková were all victorious as they began their Italian Open campaigns.
Austrian second seed Dominic Thiem made history in the men's singles final at the US Open after coming from two sets down to defeat Germany's Alexander Zverev and win his first Grand Slam.
Alexander Zverev and Jennifer Brady are the first players to book US Open semi-final places in New York City.
The French Tennis Federation (FFT) has confirmed it is pressing ahead with plans to hold the French Open with fans later this month, but the tournament will not feature defending women's champion Ashleigh Barty after she announced her withdrawal.
Victoria Azarenka of Belarus continued her strong form to reach her fifth US Open women's singles quarter-final, after coming from a set down to defeat Czech 20th seed Karolina Muchova.
Japan's Naomi Osaka enjoyed a straight sets victory over Estonia's 14th seed Anett Kontaveit in the evening session at the US Open today.
Petra Martic and Petra Kvitova became the latest top ten seeds to fall in the women's singles draw at the US Open, as they both lost in three sets.
Michael Pavitt: Return of sporting events a positive but packed schedule presents a challenge for athletes
Nearly two years ago, I wrote about my tentative support for the UEFA Nations League format with the competition providing more structured international football matches in place of meaningless friendlies, as well as pitting nations of a similar level against each other.
Tennis starlet Coco Gauff admits the postponement of the Olympic Games to 2021 has increased her chances of reaching Tokyo 2020 - something she says is "definitely the goal".
Greek number four seed Stefanos Tsitsipas is out of the US Open after a five-set defeat to Borna Coric of Croatia in round three, but Novak Djokovic advanced.