Canadian Milos Raonic suffered a new injury setback that forced him to abandon a last-16 match against home player Yuichi Sugita at the Japan Open.
Raonic and Sugita completed just one game before the third seed had to withdraw with a calf strain.
"It's hard to know the extent of it, I'll have to wait because it's too soon to have an exact evaluation," Raonic told the ATP World Tour website. "I felt a sharp pain at the back of my leg. I will head home now and get medical attention."
The tournament marked Raonic's return from a seven-week absence from the tour, which was caused by a wrist injury.
Belgian fourth seed David Goffin shook off a slow start to edge through to the quarter-finals, beating Australian Matthew Ebden 2-6 7-5 7-6 (7-1), with Frenchman Richard Gasquet and American Steve Johnson both also advancing to the last eight.
The China Open is live on Sky Sports on Friday from 5:30am on Sky Sports Action. The Japan Open is live from 4am on Sky Sports Arena.
Sky Sports Tennis will have all the action from the ATP China Open, Japan Open and Shanghai Masters before the action heads to Paris.
The Next Gen ATP Finals in Milan and season-ending extravaganza World Tour Finals at London's O2 in November end another memorable year which will covered via our website sky.mnosports.com/tennis with live blogs and updates as the season reaches its climax.
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