Jason Dufner and Zach Johnson pulled away from the field on Saturday to set up a two-man showdown on Sunday at the Crowne Plaza Invitational at Colonial.
Dufner posted a four-under 66 to finish three rounds at 15-under-par 195 for the lead.
In his last 35 rounds played, Dufner has been on top of the leaderboard after 12 of those rounds. This was his third 54-hole lead of the year, and fifth of his career.
Johnson carded a five-under 65 and is one stroke back at minus-14. The former Masters champion had a chance to tie Dufner on 18, but his birdie effort slid by the left edge.
Tom Gillis is alone in third at seven-under-par 203 after shooting 69 on Saturday. Bo Van Pelt (71) is one further back at minus-six, while Ryan Palmer (70) and John Huh (69) share fifth at five-under 205.
Dufner and Johnson matched short birdies putts at the first, but Johnson followed with a chip-in birdie on the second to get within one of Dufner's lead.
Three holes later, Johnson rolled in a seven-footer to match Dufner at minus-12. Dufner answered with a birdie on seven, but Johnson responded with a 26-footer for birdie on nine as they turned at 13-under.
Around the turn, Dufner caught fire and looked as though he would run away and hide. He rolled in a 20-foot birdie effort on the 10th, then dropped his third within four feet at the 11th and rolled that in for birdie and a two-stroke lead.
Dufner, who has won the Zurich Classic of New Orleans and Byron Nelson Championship in his last three starts, wasn't finished. He made another four- foot birdie try on 12 to go three clear of the field at 16-under.
Both Dufner and Johnson stumbled to bogeys on the 14th. Dufner missed the green at the 16th and chipped to seven feet. He wasn't unable to convert that putt, while Johnson made a 16-footer for birdie on the same hole to cut the lead to one.
Dufner hit his approach to eight feet on No. 17. Johnson's second shot rolled into Dufner's ball. After the balls were properly moved and marked, both players drained their birdie chances before they parred the last.
"I've just been working real hard on my game and I feel confident. Breaking through a couple weeks ago at Zurich gave me a lot of confidence and I'm just trying to run with it and do the same things I've done all year," Dufner said in a televised interview.
"It helps to be here this week with good control of my golf ball. You've got to use the wind in different ways and hit different shots out there. You have to have control of your swing and I feel like I'm in that place right now."
Johnson is looking for his eighth PGA Tour win, but his first since winning this title in 2010.
"The front nine I hit the ball pretty good and gave myself some opportunities. Short game was nice as well, but the back nine was a battle," Johnson said in a TV interview. "There's no reason to get ahead of myself. I just have to keep doing the same thing."
NOTES: If Dufner hangs on to win, he'll become the first player to win the Byron Nelson and Colonial in back-to-back weeks. Ben Hogan is the only player to win those two events in the same year...If he wins, Dufner will be the first player to earn three wins in a season since Jim Furyk in 2010...Dufner is 26-under par for his last seven rounds on the PGA Tour...Johnson posted his 15th straight round in the 60s at Colonial...Seven players missed the Saturday cut and 72 will play the final round.