Phil Mickelson spent his Sunday morning moving into his favorite spot of late.

The lead of a professional golf tournament.

Mickelson went to the top of the leaderboard in the 70th Masters late in the weather- and darkness-delayed third round at Augusta National Golf Club. He was the 54-hole leader at 4-under par, playing the final 13 holes of the round in 1-under par.

Mickelson, the 2004 Masters champ, began his final round aiming to become the first player since Sandy Lyle in 1988 to win the Masters a week after winning another tournament.

He won the BellSouth Classic by 13 strokes last week in suburban Atlanta.

Mickelson led Fred Couples, Darren Clarke and overnight leader Chad Campbell by one shot. Stephen Ames, Tigers Woods, Tim Clark, Darren Clarke and Rocco Mediate were two strokes back in a tie for fourth place.

While Mickelson and the leaders went to lunch, the rest of the field chased. Geoff Ogilvy, Jose Maria Olazabal, Angel Cabrera and Stewart Cink moved to 1-under par and into the top-10 early in their final rounds. Ogilvy was 3-under through seven holes of his four round, as was Olazabal through five. Cabrera made two birdies in his first three holes and Cink made an early birdie.

Rocco Mediate and Vijay Singh opened their final rounds with bogeys to join the horde at 1-under.

Mediate's early final-round struggles were no surprise. He hurt himself when his foot slipped on a swing at No. 15 in his third round.

The 43-year-old, plagued by back problems the last two years, wrenched his back on the misstep and walked gingerly the last three holes. He struggled to pick up his tee after hitting his drive at No. 18 and made double bogey to fall from co-leader to the tie for fourth.

Mickelson's lead would have been two going into the final round had he not lost a shot with a frustrating bogey on the final hole of his third round. A photographer's shutter clicked during his downswing of his tee shot.

"Come on guys, this is the Masters for crying out loud," Mickelson said as his drive drifted left of the fairway. The incident clearly affected his concentration the rest of the hole. He hit his second shot right of the green and into the gallery. Then he left his chip short of the green. He two-putted for bogey.

"Since I was a kid, I dreamt of winning this tournament and playing in this tournament," Mickelson said, "and to be leading and have a chance to win and to have that happen is upsetting."

Couples played like a young man in his prime Sunday morning. He bogeyed his third hole of the morning, No. 7, to slip to 1-under for the tournament. He rallied down the stretch, though, making back-to-back birdies at Nos. 15 and 16.

Campbell hung onto a share of second place despite a failure to stunt the bogey-string that began on his final two holes Saturday night. He bogeyed Nos. 7, 9, 14 and 16 and finished the third round with a 3-over 75.

Campbell wasn't the only player to struggle with the two-day third round. Tim Clark, who began the morning a shot back of Campbell at 5-under, lost three shots on his final two holes of the round. He double-bogeyed No. 17 and bogeyed No. 18.

Several Masters favorites stumbled Sunday morning as well. Woods made three-straight bogeys at Nos. 14, 15 and 16 to fall from 4-under to 1-under. He righted himself at No. 17, however, saving par after missing the green with his approach shot at the par-4. He then birdied No. 18 to finish at 2-under for the tournament.

Despite the logjam on the leaderboard, Mickelson and Couples were the favorites in the final round, if for no other reason than they were playing in the day's final group. The Masters winner had come out of the last pairing 15-straight years.

"I didn't put much credence in it before," Mickelson said, "but now I'm hoping it's a valid stat."