Herbert shot a three-under-par 69 in the third round and is at 20 under for the tournament to maintain an advantage over Bryson DeChambeau, who was at four under Saturday and is at 17-under through three rounds.
"Look, I enjoy it; I enjoy being in the lead," said Herbert, who won in May at LIV Golf Virginia. "It's been awesome to play with Bryson the last couple days and get to play with him again tomorrow. It's a great energy out there. Any time when you're in the lead you get good energy. I think maybe playing under pressure brings the best out of me."
England's Tyrrell Hatton (67) was alone in third place at 15 under, while Australia's Cameron Smith was also in superb form, his 66 leaving him alone in fourth place at 14-under.
Harold Varner III (68) and Mexico's Abraham Ancer (65) are in a two-way tie for fifth at 13-under.
After scorching the JCB Golf and Country Club course with an 11-under in the opening round, Herbert was far more conservative in the third round when he opened with seven consecutive pars. He closed the front nine with consecutive birdies.
After a bogey-five at the 11th, Herbert closed with a pair of birdies over his last seven holes, including a birdie-three at 18 when he put a 132-yard second shot to within seven feet from the hole.
"I am going to do my best just to stick to what I'm doing, try and make as many putts as I can," Herbert said. "I wasn't happy with my (putting) speed out there. I was a little tentative today. That's not going to happen tomorrow. I am going to make sure I get the ball to the hole and get a lot more chances."
Herbert acknowledged the challenge of trying to close out the victory against a trio of proven players in DeChambeau, Hatton and Smith.
DeChambeau put himself in line for his third victory of the season, and first since March at South Africa, with five birdies and a bogey in the third round.
DeChambeau's lone hiccup came at the par-five 10th hole when he sent his third shot just over the green and missed a 13-foot putt for par. He improved his round with a pair of birdies over the final three holes.
"I played some good golf," said DeChambeau, who gained a stroke on Herbert during the round. "I felt like I could have had a couple things go a couple different ways, but the birdies on 16 and 17 were huge for tomorrow."
Hatton, a fan favourite for the week while in his home country, made an early charge with three birdies over his first four holes, but the run was interrupted by a bogey six at the sixth.
With windy conditions expected for the final round, Hatton knows there will be additional challenges ahead.
"It's quite quirky out there, so it's easy to get a little bit unlucky with some of the slopes," Hatton said. "And you don't really have to do too much wrong to drop shots. We'll see how it goes. Either way, I think just focusing on my side, just trying to play another good round of golf, whatever the weather."
Season-standings leader Jon Rahm is in a tie for 29th at two-under par.
