Whalen defeated Pete Griffith of Westlake Village, Calif., 1-up, in this afternoon's semifinal match. Whalen never trailed in the match, and stood on the tee of the par-3 14th hole with a 3-up lead. Griffith then dropped two birdies in a row to win the next two holes, cutting into Whalen's lead. The two players traded pars for the last three holes, and Whalen held on for the 1-up win.

Whalen first entered the golf scene in 2011 when, as an unheralded player, he made it to the quarterfinal match of the 2011 U.S. Junior Amateur, being held that year at Gold Mountain Golf Club in Bremerton, Wash. In that quarterfinal match, he fell to the championship's eventual winner, a young Jordan Spieth.

Whalen, the No. 16 seed, had defeated No. 1 seed James Grierson in the Round of 16. Whalen qualified for and played in the 2016 U.S. Amateur Four-Ball, and last week held the first round lead of the Rosauers Open Invitational, a professional tournament held in Spokane, Wash. Now a senior at Northwestern University, he made it to the Round of 16 in the 2012 PNGA Men's Amateur.

In this afternoon's other semifinal match, Yuan came from behind for a 1-up victory over Drew McCullough of Richland, Wash. Yuan won three of the last five holes of the match. McCullough, who earlier this month won the Seattle Amateur and will be a junior at the University of Wyoming in the fall, had made a costly bogey on the par-4 17th which gave Yuan the lead, and when the two traded pars on the 18th, the match went to Yuan.

Yuan, who earned the No. 2 seed in the championship's stroke-play qualifying rounds, will be a sophomore in the fall at the University of Washington. Earlier this summer, he had qualified into the Sectional stage for the 2016 U.S. Open.