Rory McIlroy kept his integrity intact despite falling eight shots behind red-hot Ryder Cup teammate Sergio Garcia in the $7.5 million Nedbank Golf Challenge in Sun City.

A two-time winner at Gary Player Country Club, the in-form Spaniard made eight birdies in an immaculate 64 to lead by four shots from South Africa's Charl Schwartzel, Frenchman Mike Lorenzo-Vera and Finland's Mikko Korhonen on eight-under par.

It was a ball-striking clinic by Garcia, who missed just two greens in regulation on a day when Shane Lowry stayed on the strait and narrow to post a one-under 71 and Pádraig Harrington finished strongly for a 73.

In contrast, Paul Dunne struggled to a six-over 78 as McIlroy got little reward for a moment of honesty at the 14th as he carded an ultimately disappointing, level par 72.

Scores

If he wins this week, a solo second in Dubai next week would be good enough for McIlroy to overhaul Race to Dubai leader Francesco Molinari, providing the Italian were to finish worse then tied sixth with one other. 

Solo second for McIlroy at Gary Player Country Club and a win in Dubai would leave Molinari needing to finish worse than solo seventh or a tie for sixth with two others for him to win his fourth Race to Dubai crown since 2012.

In short, it's a tall order and while the Co Down man produced some flashes of brilliance to get to three-under par with five holes to go, he played his last five holes in three-over as Garcia birdied the 15th, 16th and 17th.

Chasing a birdie at the 601-yard 14th, McIlroy carved his drive into the thick undergrowth, then felt that he might have exceeded the allotted five-minute time limit before the ball was found and insisted on going back to the tee to reload.

He eventually made a birdie with his second ball to limit the damage to a bogey six but he got no good karma for his honesty.

Bunkered greenside at the treacherous, par-four 17th, he didn't get his recovery onto the green and then compounded his error by clumsily chipping seven feet past and missing the bogey putt.

Fresh from his third successive win in the Andalucía Valderrama Masters three weeks ago, Garcia (38) combined impressive tee-to-green play with a clinical putting display.

"It felt great," Garcia said. "I rolled the ball nicely, and I made some good putts here and there. It was one of those rounds where things happened nicely to me.

"I played pretty smart, even though I probably wasn’t swinging unbelievably. I kept it under control and guessed some of the winds right, which is always difficult here."

World No 70 Lowry drove the ball well and finished the day ranked first for putting as he mixed four birdies with three bogeys in his ongoing quest to climb back into the world’s top 50 by the Spring. 

As for Harrington (47), who will likely need a top-seven finish to make the top 60 in the Race to Dubai who qualify for next week's DP World Tour Championship, he made a birdie two at the 16th before brushing in a 35 footer at the 17th to salvage a battling 73 that left him tied for 31st on one-over.

Dunne confessed before the start that the narrow and penal Gary Player Country Club is not one of his favourite tracks.

And it showed as he hit just six fairways and saw three birdies cancelled out six bogeys and a triple bogey seven at the fifth, his 14th, as he signed for a 78 to lie 66th in the 72-man field on six-over.

At the PGA Tour's Mayakoba Golf Classic in Mexico, seven-time winner Matt Kuchar (40), Web.com Tour graduate Kramer Hickok (26) and Dominic Bozzelli fired seven-under 64's to lead by a stroke from a 15-strong chasing posse at El Camaleon Golf Club.

Former winner Graeme McDowell finished the day tied 77th on one-under after a 70 with Jordan Spieth 91st after a 71 and West Waterford’s Seamus Power tied 109th after a one-over 72.