LONDON - Five top-10 seeds, including China's Olympic champion Zheng Qinwen, crashed out of the first round at Wimbledon on Tuesday in a day of upsets and soaring temperatures.
Zheng, the No 5 seed in the women's singles draw, suffered her third consecutive first-round exit at the grass-court Grand Slam, falling to Czech doubles specialist Katerina Siniakova 7-5, 4-6, 6-1. The match was played as London endured its hottest day of the year, with temperatures surpassing 33 degrees Celsius.
"I should have done better in my service games," said Zheng, who was broken twice after leading 5-3 in the opening set. "I don't think the surface is a challenge for me. I just felt that I should raise my level in my service games today."
Siniakova, 29, a 10-time women's doubles Grand Slam champion, will face four-time major winner Naomi Osaka in the second round.
Second-seeded Coco Gauff and third-seeded Jessica Pegula were also knocked out of the women's singles on a day filled with surprises.
Gauff, the reigning US Open champion who won last month's French Open, was beaten 7-6 (3), 6-1 by Ukraine's Dayana Yastremska.
"I'm obviously disappointed how the result went today," said Gauff, 21. "Dayana started off playing strong. I think I couldn't find my footing out there today."
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Gauff, a three-time fourth-round finisher at Wimbledon, added: "I really do want to do well here. I'm not someone who wants to write myself off grass this early in my career, but I definitely need to make changes if I want to be successful here."
Pegula, meanwhile, was stunned by Italy's Elisabetta Cocciaretto 6-2, 6-3 in just 58 minutes.
In the men's draw, No 3 seed Alexander Zverev of Germany fell 7-6 (3), 6-7 (8), 6-3, 6-7 (5), 6-4 to France's Arthur Rinderknech.
Rinderknech, 29, called it the biggest win of his career. "When it's on Center Court of Wimbledon against a guy like Sascha, who is No. 3 in the world and has been there for the last probably ten years, such a consistent player, and in five sets, I can't really ask for more," he said.
Seventh-seeded Lorenzo Musetti of Italy also suffered a shock defeat, losing to Georgian qualifier Nikoloz Basilashvili 6-2, 4-6, 7-5, 6-1. However, Musetti's compatriot and world No. 1 Jannik Sinner advanced with ease, defeating fellow Italian Luca Nardi 6-4, 6-2, 6-0.
In the final match on Center Court, 24-time Grand Slam champion Novak Djokovic overcame a mid-match illness to defeat France's Alexandre Muller 6-1, 6-7 (7), 6-2, 6-2.
The 38-year-old Serbian revealed he had been struggling with a stomach upset during the match. "The energy kicked back in after some doctor's miracle pills and I managed to finish the match on a good note," Djokovic said.
Monday's opening day also saw early exits for No. 8 seed Holger Rune of Denmark and No. 9 seed Daniil Medvedev of Russia, both of whom were eliminated in the first round.
