"I wish we could go play right now", Varner said.
No third-round leader has gone on to win the tournament since its debut in 2010.
"I'm just going to stay patient tomorrow", he said.
Na found a fairway bunker at seven and settled for par but resumed his birdie binge with a 43-foot putt at the par-3 eighth, a tap-in birdie after putting his approach at nine inches from the cup and sinking a 23-foot birdie putt to start the back nine.
Kraft said he struggled judging the speed of his putts. I got it just over the ridge.
The 19-year-old Niemann already has four top-10 finishes in eight events this season and has secured special temporary membership on tour. Varner needed to make a birdie putt on either No. 17 or 18 to get there, but he parred both holes. "I hit a lot of good shots today".
Kraft finished solo second at 14 under after a birdie on the 72nd hole.
That moves him to 19 under and five shots clear.
Phil Mickelson, in his first tournament since his freakish US Open final day meltdown on the 13th green, was penalised two shots on Sunday for improving his line of play.
Fakhar Zaman turning into a big-match player for Pakistan
Fakhar and Malik both build up a terrific 107 run partnership and completely shifted the momentum towards the World No.1 T20 side. No wonder he moved up 44 spots on the table to reach No 2 with 842 points, also the best in his short worldwide career so far.
Na broke open a shootout with 12 players within four strokes of the lead by making birdies on six of seven holes starting at the fourth, making two runs of three in a row to seize command.
"And especially on the back nine, there were two or three greens that were just - they were borderline rolling too fast".
Knox, who tied for second at the French Open last week, goes to No. 5 in the Race to Dubai and will get back into the top 50 in the world.
With a 65, Kevin Na moved into third place at 13-under.
Watson wanted to honour his late father, Gerry, a Green Beret who fought in the Vietnam War.
"Big confidence boost", Na said.
Anirban Lahiri of India and Webb Simpson trailed Kraft by a stroke entering the third round.
The only drama down the stretch was who would pick up the last of the tournament's four qualifying spots to the British Open in two weeks. Hee Young Park won a playoff after she and Angela Stanford each finished at 258 in the Manulife Classic in Canada in 2013 (par 71), while Karen Stupples (Arkansas State University) shot 258 at the Welch's/ Fry's Championship in Arizona in 2004 (par 70).