A first-team all-Mountain West Conference selection at Brigham Young University, Fillmore logged one eagle and four birdies against a sole bogey for a 36-hole total of 6-under-par 134. His 65 is the lowest score of the stroke play portion of the championship.
His eagle came on the 447-yard, par-4 fifth when a 6-iron shot from 178 yards took one bounce and rolled into the hole.
'The goal was to make match play,' Fillmore said. 'To shoot 65 makes it that much better. I feel really good about the way Ive been playing.'
His 36-hole medalist score tied (with three others) for the second-lowest in Amateur history. Hank Kim shot 132 in 1994 for the lowest medalist score.
Fillmore is trailed by Wesley Bryan of Chapin, S.C., at 136; and Corey Nagy, 19, of Charlotte, N.C., and Dan Woltman of Beaver Dam, Wis., at 137.
Bryan, 18 and a freshman at the University of South Carolina, followed his 67 on No. 2 with a 69 on No. 4.
'I was two over after eight holes and I knew I had to make a move,' Bryan said. 'I wanted the medal to be honest, but Ill live. I played good. The next goal is winning. Its been a goal to win this ever since I was little.'
Nagys 3-under-par 67 came on the famed No. 2 course, which has been the site of two U.S. Opens.
Fillmore, who spent 2004-2006 on a mission in Chile and is married, did not play golf in those two years.
'You grow up pretty fast,' Fillmore said. 'I matured a lot.'
Among those advancing to match play were 2007 U.S. Walker Cupper Kyle Stanley of Gig Harbor, Wash., at 2-under 138; 2004 U.S. Junior Amateur champion Sihwan Kim of Buena Park, Calif.; 2003 Junior Amateur champion; 2005 Walker Cupper Brian Harman of Savannah, Ga., and 2007 Walker Cup team member Billy Horschel of Gainesville, Fla., at 140.
The oldest player to advance to match play is 52-year-old Brady Exber of Las Vegas who finished at 142.
A 26-player playoff for the final two berths in the match play will be played at No. 4 beginning at 7:30 a.m. on Wednesday. The 26 competitors in the playoff is the second most in Amateur history, eclipsed only by the 31 players in 1988.
Among those not advancing to match play were three past USGA champions: 2004 U.S. Austin Eaton (2003 U.S. Mid-Amateur); Danny Green (1999 U.S. Mid-Amateur) and Nathan Smith (2003 U.S. Mid-Amateur).