Augenstein, 21, a senior at Vanderbilt University and No.38 in the WAGR, reeled off birdies on holes 6-8 of the renowned Course No.2 at Pinehurst to seize control in his 3-and-2 morning victory over Bhatia, the runner-up in the 2018 US Junior Amateur and the highest-ranked played left in the field. In the afternoon, Augenstein built a 4-up lead over Castillo, and after an eagle-birdie-birdie blitz by Castillo brought him within one hole, the players tied the final six holes with pars.

“I just tried to stay in the moment and understand that I’m still winning the match,” Augenstein said. “[Castillo] still has to win two holes to beat me, and as long as he doesn’t do that, I’m going to win. I think in match play, everybody is going to go on a run. I think you expect it, and that way you’re not surprised when it happens.”

Fellow Kentuckian Austin Squires, of Union, joined Augenstein in the quarterfinals as the No.64 seed. Squires, who topped No.1 seed and World No.11 Brandon Wu in the Round of 64 on Wednesday, edged Stefano Mazzoli, of Italy, in 19 holes and held off John Pak, of Scotch Plains, N.J., 2 up, on Thursday to reach the quarterfinals for the second consecutive year.

“Just to be in the position last year was pretty cool, but to be back here again, I know what I’m up against, and ready to get after it [on Friday],” said Squires, a recent graduate of the University of Cincinnati. “John [Pak] is one of my best friends in amateur golf. I knew what I was up against today when I played against him. I just got in a zone early and then kind of tried to coast, but he didn’t let me coast.”

RIGHT: Karl Vilips has made the quarterfilans of the US Amateur Championship. PHOTO: Marcelo Endelli/Getty Images.

Squires set up a quarterfinal matchup against the youngest player left in the field, 17-year-old Cohen Trolio, of West Point, Miss. Trolio ousted Blake Wagoner, of Cornelius, N.C., 2 and 1, in the morning and rode six birdies to a 5-and-4 win over Alex Fitzpatrick, of England, in the afternoon. Fitzpatrick was a quarterfinalist in 2018 and was vying to join his brother, Matthew, for whom Alex caddied in his 2013 US Amateur victory.

Another Mississippian, Andy Ogletree, of Little Rock, joined Trolio in the quarterfinals with a 19-hole win over Maxwell Moldovan in the morning and a 5-and-4 triumph over Blake Hathcoat in the afternoon. Ogletree, 21, a senior at Georgia Tech, will take on Spencer Ralston, of Gainesville, Ga., and the University of Georgia, who ousted Julien Sale, of France, and Parker Coody, of Plano, Texas.

Twin brothers Parker and Pierceson Coody were seeking to join their grandfather, 1971 Masters champion Charles Coody, who reached the semi-finals of the US Amateur on Pinehurst No.2 in 1962. But No.12 seed Ralston eliminated Parker, 6 and 5, and No.46 seed William Holcomb V, of Crockett, Tenn., ousted Pierceson, 2 and 1.

Augenstein will face Palmer Jackson, 18, of Murrysville, Pa., who went to the 18th hole in both matches, but defeated Jacob Solomon, 1 up, and Isaiah Salinda, 2 up.

The final quarterfinal matchup will feature Holcomb and Karl Vilips, 18, of Australia, who posted matching 3-and-1 wins over Steven Fisk, of Stockbridge, Ga., and Brad Dalke, of Norman, Okla., the 2016 runner-up in this championship.