SUN CITY, South Africa (AP) - Graeme McDowell recovered from a double-bogey seven at No. 14 to birdie two of his last three holes Friday for a 5-under 67 and a one-shot second-round lead at the Nedbank Golf Challenge.

The Northern Irishman moved to 7 under for the tournament and clear of four players who shared second at Sun City.

American Jason Dufner had four birdies and no dropped shots in his 68 to go 6 under on his Nedbank debut. Robert Karlsson (69), Martin Kaymer (68) and defending champion Lee Westwood (70) were one off the lead alongside Dufner.

Top-ranked Luke Donald was tied for eighth on 3 under with his 1-under 71 after he bogeyed two of his first four holes in an inconsistent round that included four birdies and three bogeys.

Charl Schwartzel, who shared the overnight lead with Westwood, slipped to 10th in the 12-man field with a 2-over 74 at Gary Player Country Club to go to 2 under for the $5-million invitational tournament.

Chasing the $1.25-million winner's prize, McDowell collected seven birdies alongside his double bogey at No. 14, with five of those birdies coming on an incident-filled back nine.

He picked up shots at Nos. 10 and 11, chipped in for another birdie at No. 13, then pushed his tee shot into the left rough on No. 14. He took two strokes to get back onto the fairway after hitting a rock - and not his ball - with his second. He then sent his fourth into a greenside bunker and missed a six-foot bogey putt.

But McDowell pulled shots back at Nos. 16 and 18 for his one stroke lead heading into the weekend.

"It was a very calm and quiet front nine and a pretty exciting back nine, I guess," he said. "I made a couple of nice birdies around the turn, a nice chip-in at No. 13 and at 14 ... that second shot can only be described as an air shot.

"There's so much trouble lurking at this golf course, (but) a better day at the office. I enjoyed that."

Dufner's solid 68, with two birdies around the turn, one at No. 13 and a fourth at the tough, par-four No. 17 lifted him to a tie for second on his first visit to Sun City and first trip to South Africa.

"I did everything pretty well," Dufner said. "Obviously to play a round with no bogeys is gonna help a lot. I'm learning this golf course quickly and a little bit on the fly."

Karlsson carded a second straight 69 with three birdies, no bogeys and a crucial par save at No. 8 where the tall Swede nailed a 60-foot putt from the edge of the green to keep his scorecard flawless.

No. 4-ranked Kaymer had three birdies and an eagle three on No. 10 to be one off the lead, while No. 3-ranked Westwood had four birdies and two bogeys for a 2-under 70.

South Korea's Kyung-tae Kim put his approach to two feet as he birdied his first. But he bogeyed No. 2 to set the tone for an up-and-down 70 with an eagle, four birdies and four bogeys. Kim shared sixth with Englishman Simon Dyson (70).

Donald birdied No. 2 with a smooth 15-foot putt, but then bogeyed Nos. 3 and 4 on his way to 1 under for the round and 3 under overall alongside Anders Hansen.

Home favorite Schwartzel had an incredible save on No. 6 after pulling a tee shot into the bush. His second, crouching under a tree with a restricted backlift, found the middle of the green and he made par.

But the effort failed to inspire the Masters champion, who double-bogeyed No. 8, holed his only birdie on No. 9 and dropped another shot at No. 13.

Darren Clarke's back nine was even more dramatic than that of McDowell, his compatriot from Northern Ireland.

Clarke reeled off six birdies, including four in a row from No. 12, but also had a bogey and two double-bogeys to go without a par in his last nine for a 3-under 69 and 1 under overall.

The only player behind him was Italy's Francesco Molinari, whose only high so far was an eagle three at No. 2 on Thursday. Molinari had a double-bogey, three bogeys and no birdies Friday for a 77 and a 5-over par two-round total of 149.

He was six shots behind Clarke and 12 off the lead.