Tiger Woods, who began the week with back problems and has been unable to mount a charge, shot a 2-under 69 and will start the final round six shots off the pace.
Verplank shot a 3-under 68 on another day of low scoring at the Champions Golf Club to reach 13-under 200. Verplank bogeyed the par-4 18th to have his advantage trimmed to one shot over David Duval -- the British Open champion who stormed into contention with a 63.
"I hit a bad 7-iron," said Verplank, named to the Ryder Cup team for the first time in his career in September. "I was trying to force it in. I had to putt the ball through the fringe and it didn't come out the way I thought it would."
Duval eagled the par-5 fifth, bogeyed the sixth and then birdied seven of the next 10 holes.
"It was a combination of everything today," Duval said. "It was just good golf. The golf course is immaculate and there's virtually no wind out there. If you're hitting the ball well, it's there for you to score low."
"I teed off in the very first group on Thursday morning and my goal was to go from the first group on Thursday to the last group on Sunday and I almost made it," Estes said. "I played great today but I'm not passing anyone on the leaderboards. Everybody's playing great."
"I'm obviously very happy. I was frustrated by the way I played the first two days," Furyk said. "Today, the floodgates opened and I took advantage of those opportunities to make birdies. I didn't make any long putts but I was hitting it close and was making the short putts."
Only four of the 29 players in the exclusive field failed to break par. The tournament is open only to the top 30 money winners on the PGA Tour, but Phil Mickelson withdrew to be with his family after the recent birth of his second daughter.