Zhang Shuai of China competes during the women's singles round of 32 match between Amarissa Toth of Hungary and Zhang Shuai of China at the WTA 250 Hungarian Grand Prix in Budapest, Hungary on July 18, 2023. (Photo by Attila Volgyi/Xinhua)

Slowly but surely, the cruelly demanding nature of professional tennis has taken its toll on Chinese veteran Zhang Shuai.

After suffering 16 singles losses in a row since February, Zhang's withdrawal from the US Open was announced by tournament organizers on Tuesday, ending her impressive run of 30 straight main-draw appearances at the majors.

Zhang, who reached the fourth round last year to mark her best run at Flushing Meadows, had not responded to the announcement at the time of going to print, yet a series of disappointing defeats and setbacks on and off the court suggested the 34-year-old would have been unlikely to return to winning ways in New York.

In addition to a nagging shoulder injury, Zhang admitted during this year's Wimbledon that the stresses of competing on the tour away from family had worn her out physically and mentally, and left her feeling barely any joy in playing tennis.

"I feel quite exhausted, especially tired mentally," she told Chinese media after crashing out in the first round at the All England Club last month.

"I've been competing overseas without going back home for two and a half years. I play at the same tournament at a certain time every year, eating at the same players' lounge and going to the same Chinese restaurant in the same city repeatedly.

"I feel like I've lost the passion and motivation to play the game, and I've almost reached my limit. I really need a long break," she said of her losing streak that began with a second-round defeat to Belgium's Maryna Zanevska in Lyon, France on Feb 2.

As a late bloomer on the women's circuit, Zhang's career has been defined by resilience, perseverance and discipline, which helped her achieve a major breakthrough at the 2016 Australian Open, where she fought all the way from the qualifiers into the quarterfinals.

She had racked up 14 opening-round defeats at the Slams over a span of eight years prior to that breakout triumph in Melbourne.

With her confidence rebuilt, Zhang went on to reach another singles quarterfinal (Wimbledon 2019) and the round of 16 three times on the major stage, as well as winning two Grand Slam doubles trophies with Sam Stosur, at the 2019 Australia Open and the 2021 US Open.

However, the recurrence of her injury and conditioning issues have derailed her attempt to stay competitive in the top echelon since she won her third career WTA singles title in Lyon in March 2022.

An incident at the Hungarian Grand Prix last month dealt Zhang another tough mental blow.

Serving at 5-5 in the first set against local favorite Amarrisa Toth, the Hungarian player wiped away a ball marking on the clay court, much to the annoyance of Zhang, who wanted the mark checked again.

TV replays appeared to show the forehand winner was in, yet the shot was called out by French umpire Morgane Lara, who upheld her ruling after leaving her chair to check the mark upon Zhang's request.

With Zhang pleading with Lara to reverse the decision, Toth appeared to laugh as the crowd began to jeer the Chinese player.

After losing that service game, Zhang teared up during the changeover and eventually decided to retire from the match.

Toth celebrated by raising a clenched fist just after a tearful Zhang had shaken her hand and that of the umpire.

Toth later apologized to Zhang for her insensitive behavior in a video posted on social media after being condemned by fellow players and fans worldwide.

This week's announcement, though, seems to indicate that the emotional scars of that incident have not fully healed and she is struggling to rediscover her focus.

Zhang's withdrawal from the US Open, which begins on Aug 28, has raised concerns among fans that the world No 48 could hang up her racket for good.

However, Zhang insisted at Wimbledon that taking a long break might just be the tonic.

She may also take solace from her career-redeeming run at the 2016 Aussie Open when she overcame mental fatigue in the buildup to that tournament.

"I feel really frustrated and tired at the moment but I hope I am not done yet," she said back then.