Beijing, Sept. 25 -- France's Alexandre Muller produced a major upset at the China Open, 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 here.

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 on Wednesday.

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 roun...