Rory McIlroy and Jordan Spieth are five shots off Branden Grace’s lead after day one of the WGC-HSBC Champions.
South African Grace’s nine-under 63 gave him a one-shot lead over three players in Shanghai, while USA’s Dustin Johnson and Patrick Reed and England’s Danny Willett are two back.
McIlroy played despite struggling this week with food poisoning.
“It was probably a little better than I was expecting out there to be honest,” the world number three said.
“When I was hitting balls this morning on the range I had not been out of bed for basically 48 hours, so I was really stiff,” added the 26-year-old Northern Irishman.
“I needed to loosen up quite a lot, but when I got out there I felt pretty good.
“I’ve lost 10 pounds since being here. I can’t remember the last time I was this light. But hopefully if I have a couple of good meals over the next couple days and rehydrate and I’ll be feeling a lot better.”