Andy Murray's Zhuhai Open campaign was halted in the second round as he slipped to a 6-4, 2-6, 4-6 defeat against a dogged Alex De Minaur.
Murray, who edged past Tennys Sandgren on Tuesday, looked in good shape when he broke twice on his way to claiming the first set, but De Minaur recovered.
The 20-year-old Australian came out on top in some riveting rallies, with a sublime drop shot in set three a highlight as Murray's lack of match sharpness handed De Minaur the edge.
De Minaur had squandered two break points at the start of the third set, though he made no such mistake to take a 5-4 lead eight games later.
Former world number one Murray kept his chances alive with some exquisite shots, only to waste three break-back points.
Having then failed to take a first match point, De Minaur made his second one count – Murray's return into the net ending a contest lasting two hours and 42 minutes as the Australian progressed to a quarterfinal with Borna Coric.
Murray will turn his focus to the China Open in Beijing as the British player continues his singles comeback following hip surgery.
Greek top seed Stefanos Tsitsipas retired due to illness prior to the third set of his encounter with France's Adrian Mannarino.
Damir Dzumhur will face Mannarino in the last eight, while second seed Roberto Bautista Agut goes up against Andreas Seppi, who saved five match points in a deciding-set tie-break en route to beating Zhizhen Zhan 7-6 (7-4), 4-6, 7-6 (10-8).
Meanwhile, Chengdu Open top seed John Isner fell at his first hurdle as the American succumbed 6-7 (11-13), 7-6 (7-5), 7-6 (7-4) to Egor Gerasimov of Belarus.
Gerasimov – who will next play Denis Shapovalov – was joined in the last eight by US Open semifinalist Grigor Dimitrov, who marked his return to action with a 7-5, 7-5 victory over Britain's Dan Evans.
Canadian second seed Felix Auger-Aliassime went down 6-4, 6-7 (5-7), 6-4 to Portugal's Joao Sousa, Spaniard Pablo Carreno Busta defeated Frenchman Benoit Paire, while Chile's Cristian Garin dispatched Fernando Verdasco of Spain.