Jason Kokrak rallied with four consecutive birdies as a stellar back nine helped the American claim the Houston Open.

Kokrak carded a five-under-par 65 for an impressive two-shot victory and his third PGA Tour trophy at Memorial Park on Sunday.

The 36-year-old was two strokes behind with six holes to play before birdieing the 13th, 14th, 15th and 16th to trump countrymen Kevin Tway (68) and overnight leader Scottie Scheffler (69) to glory.

"Very blessed to be standing here," Kokrak said afterwards in Houston, where he found himself 10 shots adrift after two rounds.

Kokrak, who went 232 starts before his first PGA Tour victory, has now won three titles in his last 27 starts, dating back to October's CJ Cup.

"This win is very special. I was really struggling with my game at the beginning of this week," Kokrak added.

"But I was on the phone with my swing coach and worked on a few things and that worked really well. So, I have to thank him and my caddie, it was really tough at times out there."

Tway and Scheffler finished tied for second, while Kramer Hickok shot a final-round 69 to be outright fourth at seven under as Joel Dahmen (65) and Martin Trainer (70) ended the tournament a shot further back.

At the other end of the spectrum, former world number ones Adam Scott (73) and Jason Day (70) closed out the event at five over, two strokes better off than 2018 Masters champion Patrick Reed (77).

Scottie Scheffler moved to the top of the leaderboard after a long but fruitful day at the Houston Open, taking a one-stroke lead into the final round. 

After Friday's second round was halted due to darkness, players had to return to the course early Saturday to finish before starting the third. 

Scheffler wrapped up the second round by setting a course record with an eight-under-par 62, then carded a 69 in round three to take the overall lead at seven under for the tournament. 

The American has held or shared the lead after 54 holes only once before, at the 2020 American Express, where he finished third. 

Martin Trainer moved to the top of the Houston Open summit before play was again cut short due to darkness.

Like the opening round, players were forced from the field in Houston as fading light brought a premature end to Friday's second round.

Trainer managed to complete his second 18 holes and found himself in rare territory, a stroke clear at Memorial Park.

Back-to-back 65s left the 2019 Puerto Rico Open champion atop the leaderboard, with a number of players yet to finish their rounds as the PGA Tour tournament continues to play catchup.

"Last week I hit the ball really well for the first time in a long time and I just didn't putt very well," said Trainer, who had one made cut in his last 18 starts entering the event.

"So I figured if I could somehow do both those at the same time -- to be fair, every single player says that every single week. But for me, it had been such a long time coming. It really was a grind for a long time.

"So now to finally be able to put it together ... you have to hope that this is the week."

Fellow American Kevin Tway ended the day a shot behind Trainer, while Jason Kokrak was on track to seize the lead at eight through 11 holes.

The second round will be completed on Saturday and Brooks Koepka is set to miss the cut for the second consecutive week.

Four-time major champion Koepka shot a second-round 72 to be three over, below the projected cut of one over.