China's top-ranked male tennis star Zhang Zhizhen outlasted American J.J. Wolf in a five-set thriller to claim his first ever victory in the main draw of the U.S. Open, and his win on Monday added to a number of other positive results for the Chinese contingent. 

Under the weight of immense pressure, the 26-year-old Zhang displayed remarkable poise and resilience, prevailing over the formidable world number 45, Wolf,  7-5, 7-5, 6-7 (5), 4-6, 6-3 at the USTA Billie Jean King National Tennis Center in New York.  

Awaiting Zhang in the upcoming second round is a thrilling showdown with none other than the Norwegian No. 5 seed, Casper Ruud. This highly anticipated encounter promises to be a clash of titans, pitting two exceptional talents against each other in a battle for supremacy on the tennis court. 

In recent months, Zhang has achieved a remarkable array of tennis "firsts" for China. In October of last year, he etched his name in history by becoming the first men's singles player from the Chinese mainland to break into the top 100 in the ATP's world rankings.  

Then, in May, he further solidified his place in the annals of Chinese tennis by becoming the first to advance to the quarterfinals of an ATP Masters 1000 event at the Madrid Open. And, as if that weren't enough, he also claimed the title of being the first men's player from the Chinese mainland to win a main draw match at the illustrious French Open.  

Meanwhile, Zhang's compatriot Zhu Lin managed to start off on the right foot after outclassing Egyptian Mayar Sherif 6-3, 7-5. This victory marked a significant milestone for the 29-year-old, as it was her first win in the U.S. Open main draw since 2019. Currently ranked at No. 44, Zhu now faces a stern challenge in the form of Belarusian powerhouse Victoria Azarenka, the No. 18 seed.

Later in the day, Wang Xinyu romped past American qualifier Katie Volynets 6-3, 6-4 in their first-round clash, while Wang Xiyu also stormed into the second round after knocking out Slovak lucky loser Viktoria Hruncakova 4-6, 6-3, 7-6 (6). 

Elsewhere in the women's draw on Monday, the world number one, Iga Swiatek, commenced her U.S. Open title defense in extraordinary fashion, delivering a resounding 6-0, 6-1 victory over Sweden's Rebecca Peterson in a mere 58 minutes.  

Swiatek, who is vying for her fifth Grand Slam title, now sets her sights on a second-round encounter with Australia's Daria Saville. Notably, no woman has accomplished the feat of retaining the U.S. Open title since the legendary Serena Williams achieved this remarkable feat three consecutive times from 2012 to 2014. 

In a surprising turn of events, Greece's eighth seed, Maria Sakkari, encountered a disappointing fate as she suffered an early exit from the tournament. Despite her high ranking, Sakkari was stunned by Spain's Rebeka Masarova 6-4, 6-4.  

Former U.S. Open champion Sloane Stephens also had a day to forget as she fell 6-2 5-7 6-4 to Brazilian 19th seed Haddad Maia, who is through to the second round for just the second time.