France's Alexandre Muller produced a major upset at the China Open on Wednesday, coming from one set down to defeat fifth seed Karen Khachanov 6-4, 6-7(5), 6-4 in the men's singles first round at the Diamond Court of the National Tennis Center.

Wang Xiyu hits a return in the game. [photo:xinhua]

World No. 10 Khachanov squandered a 4-2 lead in the second-set tiebreak, as Muller reeled off five of the next six points to force a decider. In the final set, the Frenchman broke in the opening game, was immediately pegged back, but struck again in the ninth game and held serve to seal the victory after two hours and 37 minutes.

Ranked 84th in the world, Muller will next face Hungary's Fabian Marozsan, who defeated Frenchman Benjamin Bonzi 7-6(1), 6-3 in the opening round. The 57th-ranked Marozsan has won both of his career meetings with Bonzi.

On the Lotus Court, China's Wang Xiyu beat compatriot Guo Hanyu 7-5, 6-1 to claim her first-ever main draw victory at the China Open. The 24-year-old left-hander advanced to the second round after one hour and 33 minutes.

"I'm really happy. I see myself improve this year. I will work harder towards my goals," Wang said. She will next face Czech rising star Linda Noskova, the 26th seed of the tournament.

Later on Wednesday evening, top seed Jannik Sinner of Italy, currently ranked world No. 2, will take to the Diamond Court for a headline clash against Croatia's Marin Cilic, the former US Open champion.