On a day that started with six players tied for the lead and 52 within six strokes of the top, Clark finished a bogey-free 6-under 64 with three birdies and an eagle on his final five holes. Then he watched as his 5-under 205 total held up for a two-stroke lead as he looks for his first PGA TOUR victory.
Gusting winds that had made par a valuable score through the first two rounds eased enough to make club selection a bit easier, but the wind often came up or changed directions at the wrong time. With the greens remaining firm, scoring consistently remained a problem with 15 players under par through 54 holes.
Clark will play in the final round Sunday with countryman Trevor Immelman, the Masters champ. Immelman had his own opportunity to grab a share of the lead but bogeyed No. 18 to finish with a 67. He was tied at 207 with Bill Haas (67), Alex Cejka (69) and two of the second-round leaders in TOUR rookie Marc Turnesa (70) and Gavin Coles (70).
Vijay Singh (70), 2005 winner Justin Leonard (67), Stephen Ames (68) and Dean Wilson (71) were three strokes back at 208.
Clark started the day at 1 over and got to even with a birdie on the par-4 second. He strung together 11 straight pars before he finally got to scoring.
Hoping for par on the par-3 14th with water guarding the front of the green, Clark rolled in a 28-footer from the left fringe for birdie. He followed with a 12-footer on No. 15 that dropped him to 2 under.
The big swing came on the 530-yard par-5 16th.
Clark had 248 yards to the hole for his second shot, pulled a 5-wood and hit it within 5 feet pin-high. His eagle putt dropped him to 4 under and into a four-way tie for the lead with Haas, Coles and Wilson. Clark took the lead to himself when he stuck a 9-iron from 147 yards to 4 feet, which he sunk for birdie and to finish off a 64 that matched the lowest score shot here this week.
The six-way tie had been the most at any round on the PGA TOUR since six were tied through 36 holes at the 2007 Shell Houston Open.
That resulted in an all-out scramble with the lead changing out nearly every hole with two- and three-way ties for the top of the leaderboard. First it was Coles, then Wilson held a solo lead. It became a four-way tie when Clark eagled the par-5 16th, and he became the clubhouse leader finishing up at 5 under with a 64 that matched the low round at this tournament so far.
Then Turnesa birdied the par-5 15th and joined Clark at 5 under. Turnesa had his own chance to take the lead at the 16th but hit his second shot right of the green into the rough. His third shot across the green to the rough, and he couldnt sink a 9-footer to save par.
Tournament officials announced the 2009 event will played June 8-14, keeping its date the week before the U.S. Open for a third straight year.