Zheng Qinwen is so popular and bright a star in the professional tennis world even brand logos, coveting her huge exposure, have been seen on her opponent in a bid to share the limelight.

Halfway into her second-round match against Laura Siegemund at the Australian Open, fans watching TV at home on Wednesday morning soon captured an intriguing tiny detail on the German veteran's attire — a newly-added logo of what appeared as a Chinese brand on the front of her dress that wasn't there just two days ago during her opening-round match.

Zheng's surging popularity, and the attention that comes with it, has apparently made almost everything and everyone around her, and even against her in Wednesday's case, marketable to potential sponsors.

Yet, fame comes at a cost and the reigning Olympic champion learned it the hard way as Zheng suffered a major upset at the hands of Siegemund, who stunned the world No 5 with a 7-6 (3), 6-3 win at the John Cain Arena that put an abrupt end to Zheng's attempt of repeating her final run of last year.

Zheng, who's had a breakout second half in 2024 anchored by an Olympic gold medal in Paris, admitted that she's not 100 percent physically ready for the major challenge.

"I got some small issues (with my right elbow) after the WTA Finals. I even was discussing with my team if we have to come to play the Australian Open or not," Zheng, who narrowly lost to world No 1 Aryna Sabalenka in last year's final, confessed at the post-match news conference on Wednesday.

"I carried the pain with me into this tournament. I felt it sometimes in my swings and to contain it I had to cut short my practice sessions. So yes, it affected my game," said Zheng, who skipped all the warm-up tournaments before the season-opening major this year.

Zheng also revealed after Wednesday's loss that she had to begin her off-season training later than normal last month, due to fatigue from a busy 2024 season and off-court assignments for advertising shoots for her increasing list of sponsors.

Still, the 22-year-old big-serving star, who's racked up four singles titles on the WTA Tour to go with the Olympic gold, refused to make excuses for her poorer-than-expected performance.

"I tried what I can do during this match but I feel maybe today was not my day," said Zheng, who struggled with her serves throughout the match. She landed only 56 percent of her first serves.

"There are a lot of details at some important points that I didn't make the right choice. I had a lot of chances to break her in the first set, but maybe my concentration was not there. I always gave some easy mistakes in those moments.

"Even with the elbow issue, I still believed I had the chance to win today. ...I felt I didn't have that extra energy and extra strength in the first-set tiebreaker."

With her surprising defeat of last year's finalist, Siegemund, who entered this year's AO at No 97, has won more than just the 70 ranking points and nearly $180,000 prize money for making into the third round at Melbourne Park.

Little known in China before Wednesday, Siegemund now has made her presence felt in the emerging tennis market and has earned an endorsement deal, at least for a day, from a Chinese company.

"I knew I had to play more than my best tennis," Siegemund, who is expected to rise to top-80 with the victory over Zheng said in her on-court interview.

"I had nothing to lose, so I just told myself to swing freely. (Zheng) is an amazing player, just one of the best players right now.

"But I know that I can play well and I just wanted to show that to myself and make it a tough fight."

As a former top-30 player, Siegemund came into this match having posted four wins against top-5 opponents in her career, although all of those previous wins had come at Stuttgart, her career-best tournament on home soil where she was champion in 2017 and runner-up in 2016.

On Wednesday, though, Siegemund was performing as if she was on her beloved indoor clay of Stuttgart's Porsche Arena. Firing return winners almost at will and finding passing winners with ease.

Zheng was able to battle back and push the first set into a tiebreak, but the German would not be denied. Siegemund successfully read most of the power plays from Zheng throughout, and she won the last five points of the breaker to light up the upset alert.

By ousting the Chinese title contender, Siegemund reached the Australian Open third round for the second time in her career after reaching there in 2023.

"It's nice to be in the third round (again). I didn't expect it. My goal was to win a match here and defend my points. Singles is not my priority anymore, but at the same time I know what I can do. I know my game is there," said Siegemund, who's more focused on the doubles since winning the 2020 US Open title with her partner Vera Zvonareva of Russia.

sunxiaochen@chinadaily.com.cn