AUGUSTA - Even with Tiger on the prowl, Trevor Immelman stuck to open spaces in the third round of the 72nd Masters Tournament.

Immelman, the 36-hole leader, hit all but one fairway and 15 greens to take a two-shot lead on the field and a six-shot advantage on Tiger Woods going into today's final round at the Augusta National Golf Club.

Immelman fired a 3-under 69 Saturday and is 11-under for the tournament. Brandt Snedeker is two shots back at 9-under followed by Steve Flesch at 8-under and Paul Casey at 7-under.

Immelman, a 27-year-old South African, has never finished better than fifth in a major championship. He's hoping ignorance will be bliss today.

"I've never had the lead in a major going into the final round," he said. "I have to believe in myself tomorrow and hope for the best."

The player in fifth place - Woods -- is the one most will focus on. He posted a 4-under 68 to shave a stroke off his seven-shot deficit. He played a bogey-free round, posting four birdies, two on the par-5s.

Woods hit 11 of 14 fairways and 15 greens and might have shot an even lower score if more putts had fallen. He needed 30 putts, more than three of the four players in front of him.

Still, he's optimistic about a Sunday comeback.

"I've put myself at least in position to win the tournament," Woods said. "If the conditions are what their supposed to be, I won't have to go low."

The weather forecast calls for cooler temperature and high winds. Yet history makes Woods an underdog. He's never won a major championship when trailing after 54 holes.

And six strokes will be a challenge to make up with four players in front of him.

"You know somebody is going to play good golf," Casey said. "You look at the top-three guys up there (Immelman, Flesch and Snedeker) and one of them will play good golf. It has to happen. It will probably be Trevor the way he's playing."

Immelman looks like the safe pick. He's posted sub-70s rounds all three days at Augusta National Golf Club, the only player in the field to do so. He leads in fairways and greens hit and has made just two bogeys all week.

Snedeker and Flesch are playing like poised contenders, too. Both maintained their position near the top of the leaderboard Saturday by playing steady golf.

Snedeker, the reigning PGA Tour rookie of the year, came into Saturday's play one shot behind Immelman. He took over the lead with a birdie at No. 8 only to lose three strokes when he bogeyed the three holes that make up Amen Corner. But instead of folding, he rallied with birdies at Nos. 14, 15 and 18.

"I wasn't surprised that he came back; he's a fantastic player," said Immelman, his playing partner. "He's only been a pro a couple of years so for him to do that at this point in his career is an incredible achievement. But I still wasn't surprised."

Flesch avoided the near catastrophe that Snedeker encountered. He followed up his second-round 67 - the top round of the tournament so far - with a 3-under 69 Saturday. He made four birdies and four bogeys and posted nine straight pars early in his round.

Flesch's playing partner didn't fare so well. Phil Mickelson came into the day trailing by three shots and the frontrunner that most stood out considering he's won two of the last three Masters.

But Mickelson backed off the leaderboard instead. He shot a 3-over 75, coming apart when his pitch shot at the par-5 eighth hole bounced off the flag stick and nearly rolled off the green. He made bogey there and two more at Nos. 10 and 12.

Mickelson looked to rally as he exited Amen Corner. He birdied the par-5 13th hole and made another at No. 14.

But an aggressive play at the par-3 16th hole cost him, as he hit his tee shot into the right bunker. The pin was tucked near the right edge, and with the green sloping away from him, his bunker shot rolled 40 feet down the hill. Mickelson three-putted for a double bogey that leaves him nine shots off the lead going into today.

Another big name also made costly gaffes Saturday. Retief Goosen, a two-time U.S. Open winner, was 4-under for the tournament through 16 holes of his third round. But he bogeyed the final two holes to join Mickelson and seven others in a tie for seventh.