Unheralded South African Tim Clark grabbed the lead at the Masters, finishing off a 4-under 32 on the front side as the golfers returned to the course to complete the rain-delayed third round Sunday morning.

The stumpy Clark, who is usually overshadowed by countrymen Ernie Els and Retief Goosen, took his overall score to 6 under at the turn, going past struggling 36-hole leader Chad Campbell.

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Tiger Woods, the defending champion and four-time Masters winner, was right in the mix at 3 under with birdies on two of his first four holes in the morning. But he also made two uncharacteristic mistakes, putting his second shot at No. 11 into the water and three-putting on the difficult 14th green.

Campbell and Rocco Mediate were two strokes behind Clark at 4 under. Tied with Woods in fourth were Phil Mickelson and Stephen Ames, a native of Trinidad and Tobago who qualified for the Masters with his victory in The Players Championship two weeks ago.

Campbell and Mediate were going the wrong way.

Campbell, who had a three-stroke lead after the second round, bogeyed his final two holes Saturday evening and had two more bogeys Sunday for a 38 at the turn. Mediate took bogey at the seventh and eighth holes, though he was still 1 under for the round at the halfway point.

Mickelson birdied the par-5 eighth and had a 34 on the first nine. He gave a shot back with a bogey at the difficult 11th.

The third round was delayed more than four hours Saturday when thunderstorms moved through the area. The leaders didn't get on the course until early evening, with Campbell managing to play four holes before darkness forced another suspension of play.

It was the fifth straight year the Masters was halted by bad weather, but there were no such concerns on Sunday. The morning round began under clear, sunny skies, with chilly temperatures expected to warm up to about 70 degrees.

After finishing up the third round, the players get a short break before returning for the final 18 holes in the afternoon.

Campbell shot a 5-under 67 Friday and started with two straight birdies when he finally got on the course just before 7 o'clock Saturday evening, putting him four shots clear of the field. But the margin quickly narrowed when he bogeyed the next two holes, going off for a short — and surely — restless night with only a one-stroke lead.

The 5-foot-7, 150-pound Clark was an unlikely leader on the bulked-up course, which was lengthened to 7,445 yards — the second-longest in major championship history — and was playing even longer after the rain.

Els, a two-time Masters runner-up, began to fade from contention in the third round. He was 4 over through 11 holes, pushing his overall score to 2 over — eight strokes behind Clark.

Canada's Mike Weir, who won the tournament three years ago, also hurt his chances with a double bogey at the par-5 13th.