(Reuters) - South African Branden Grace shot a sparkling nine-under-par 63 to take a one-shot lead in the opening round of the WGC-HSBC Champions on Thursday while Rory McIlroy overcame a bout of food poisoning to finish the day five strokes back.
The world number three had been bedridden for two days and missed out on practice rounds at the Sheshan Golf Club in Shanghai, and while he did not look back to full health he still carded a four-under 68 to sit in a tie for 16th.
It was a score matched by world number two Jordan Spieth, defending champion Bubba Watson and South African major winners Charl Schwartzel and Louis Oosthuizen in an opening round delayed 30 minutes because of heavy fog.
When the fog lifted it was Grace who saw the hole clearest, the 27-year-old from Pretoria rolling in a short birdie putt on his last, the ninth, to sign for a 63 and break out of a four-way tie at the top of the leaderboard.
Grace took advantage of the soft conditions following heavy rain on Wednesday evening to fire some pinpoint irons in his bogey-free round at the $8.5 million event, which Watson won with an 11-under total last year.
American Kevin Kisner, Australian Steven Bowditch and Dane Thorbjorn Olesen all fired 64s to sit one back of the world number 22.
American Dustin Johnson, chasing his second WGC title of the year after his Cadillac Championship win in March, produced another dazzling display of long hitting before finishing with a seven-under 65.
The 2013 champion was also inches away from a hole-in-one at the 197-yard fourth.
Seven-under was good enough for a share of fifth alongside compatriot Patrick Reed and England's Danny Willett, who is second in the European Tour's Race to Dubai standings behind McIlroy with two events remaining after this week.
McIlroy's participation had been in doubt due to his illness but he loaded up with antibiotics and painkillers before producing a six-birdie effort.
The round could have been even better but for a double bogey six on his sixth hole and a cold putter.
Double major winner Spieth scrambled well in his 68, his first outing since last month's Presidents Cup win, overcoming a lost ball at the par three 17th following a wild tee shot.
"I hit one or two stray shots but that back nine, two-under the last three, was fantastic. I stole a couple there and I'm pleased with four-under," the Masters and U.S. Open champion said.
(Writing by Patrick Johnston in Singapore; Editing by Peter Rutherford)