The 20-year-old from Moscow, Idaho, is among 16 players who advanced to match play, which begins at 8 a.m. Friday. The group includes the Nos. 1 and 2-ranked amateurs Patrick Cantlay and Peter Uihlein, reigning U.S. Junior champion Jordan Spieth, 2010 Western Amateur finalist Gregor Main, 2009 Western Amateur champion John Hahn, and 2010 Western Junior champion Patrick Rodgers. The event is open to the public, and admission and parking are free.

Cantlay snuck in to the Sweet 16 by winning a playoff against Michael Cromie with a birdie on the second hole of sudden death. As the 16th seed, Cantlay will face off against No. 1-seeded Williams in Friday’s opening match.

A junior at Washington, Williams broke the record of 15-under par set in 2004 by current PGA Tour pro Aron Price at Point O’ Woods G. & C.C. in Benton Harbor, Mich.

In his two rounds Thursday, Williams shot a 1-under par 70 and a 5-under 66 after posting back-to-back 66s in the first two rounds.

“This was absolutely the best consecutive rounds of golf I’ve played,” said Williams, who attributed his success to improved putting.

“I was getting too caught up in thinking I had to make every putt instead of hitting it on the line and accepting the results,” Williams said. “I talked to my brother and my coach and they just told me to relax and accept that you’re not going to make every putt. I just focused more on the process and less on the outcome.”

Cantlay, 19, who hails from Orange County in California, made a 10-foot putt for birdie after watching Cromie miss a 12-footer on almost the same line on the 9th hole.

“I had the same putt this morning for par and missed it left,” Cantlay said. “I missed [getting into the Sweet 16] in a playoff last year, so it’s good to get in.”

Big names missing the Sweet 16 were No. 3-ranked Tom Lewis of England, No. 4 Russell Henley, and defending champion David Chung.