Herbert completed the group stage with an unblemished 3-0 record after he defeated Ben Griffin 3 and 1 in a high-quality contest.

As the winner of group 14, Herbert earned a shot at group three winner McIlroy, who also advanced with a 3-0 record.

The winner of the round of 16 clash in the early hours of Saturday morning (AEDT) advances to a quarter-final clash with the winner of the Xander Schauffele-J.J. Spaun contest.

"He's not the best player in the world right now, he's top two or three,'' Herbert said of his clash with McIlroy.

"I'm going to have to turn up with my game again tomorrow, he's not going to give it to me easily.

"We've got a hard task ahead of us, but if I play like I did the last three days, there's no reason why I can't take it to him."

After shooting 23-over par in two rounds at the Players Championship a fortnight ago, Herbert showed great mental strength to return to his best form.

Through three days he leads the event in scoring at 21-under par.

In his third round win over Griffin, Herbert made seven birdies and an eagle in 17 holes.

He was 4-up through eight holes before Griffin made a charge on the back nine.

Griffin played some great golf to cut the deficit to one hole with three holes remaining.

Herbert sunk a testing seven metre eagle putt on the 16th to regain a two-hole lead and then put the icing on the cake by making a birdie on the par-three 17th to clinch victory.

By qualifying for the last 16 at Austin Country Club, Herbert will likely earn enough ranking points to move from 56th in the world to inside the top 50 and an automatic berth for the US Masters at Augusta next month.

Round of 16 matches:

Billy Horschel v Cameron Young

Rory McIlroy v Lucas Herbert

Patrick Cantlay v Sam Burns

Max Homa v Mackenzie Hughes

Xander Schauffele v J.J. Spaun

Andrew Putnam v Kurt Kitayama

Matt Kuchar v Jason Day

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