Purdy, a winner last year on the Nationwide Tour, will be in search of victory No. 1 on the PGA Tour. If he makes it to the winner's circle on Sunday, Purdy will become the fourth first-time champion on tour this season, including the man chasing him.
'I fill out all of these goals and winning a PGA Tour event is No. 1,' said Purdy, who captured the 2003 First Tee Arkansas Classic. 'It's good to be here. I've got one more day.'
Stephen Ames posted a 3-under 68 and joined Patrick Sheehan, who carded a 69 on Saturday, in a tie for third place. The duo is knotted at 7-under-par 206.
Reigning British Open champion and overnight leader Ben Curtis struggled badly on the back nine Saturday. He tallied three bogeys and a double bogey for a round of 4-over 75 and a share of 13th place at minus-4.
Purdy began the round two strokes behind Curtis but wasted little time in moving up the leaderboard. He tapped in a birdie at the par-5 second, then ran off three consecutive birdies from the fourth, all from the 15-foot range.
Purdy already erased the gap and assumed the top spot on the leaderboard. He sank a 12-footer for birdie at the ninth, but Curtis stayed in the hunt and Purdy's lead remained at two.
Curtis looked to be in severe trouble when his second at the 11th landed in the trees. He chipped in for par, his fourth hole-out of the tournament, but Purdy in the group ahead put more distance between the two.
Purdy drained a 12-foot birdie putt at the 12th and that's when Curtis began his slide. The British Open champion missed the fairway and green at 12 and made bogey. Curtis went 4 over the rest of the way and it looks like victory No. 2 on the PGA Tour might be out of reach.
Purdy, however, played steady golf, except for a miscue with the driver at the par-5 15th. His drive went right into the trees and after pondering several options, Purdy elected to pitch out to the fairway. Purdy had 231 yards to the hole so he laid up short of the green. His fourth landed 50 feet past the hole but spun back to 10. Purdy missed the par-saving putt but still held a three-shot edge over Slocum, who birdied 12 to reach 8 under for the tournament.
At the 16th, Purdy missed the fairway again, but had an 8-iron to the green. His approach stopped 18 feet from the hole and his putt fell in the center of the cup.
He parred his final two holes and when Slocum mixed a birdie and a bogey over his last three, Purdy found himself in unfamiliar territory - the lead after a round on the PGA Tour.
Now he's in the final group on Sunday looking for win No. 1.
'Darren Clarke said I'm a hell of a player, I just need to believe it for myself. And I do,' said Purdy. 'As long as I trust my stuff tomorrow, I'll be fine. I can hang on.'
Despite a four-stroke lead, Purdy does have to contend with Slocum on Sunday. Slocum managed a 1-under 70 on Saturday to hold on to his spot in second place.
Slocum cut Purdy's lead to three with a birdie at 16 but a poor drive at the closing hole hurt him. He had over 200 yards for his second shot and failed to save par, dropping four behind Purdy.
Ernie Els, the runner-up to Phil Mickelson last week at the Masters, shot a 3-under 68 and is part of a group tied for fifth place. Kevin Na (70), 50-year-old Jay Haas (70) and Fred Funk (69) joined Els at 6-under-par 207.
Justin Rose, who led at Augusta National after the first two rounds, carded a 5-under 66 and shares ninth place with Clarke (71), Jonathan Kaye (68) and Bay Hill champion Chad Campbell (70), That group is knotted at 5-under-par 208.