Vongvanij finished the first two days of the tournament at 8-under-par to lead the group of 64 golfers qualifying for match play, which gets started Wednesday and concludes with Saturday's 36-hole championship final.
A semifinalist in 2005, Vongvanij lost to eventual champion Kevin Tway, the son of PGA TOUR player Bob Tway. On Tuesday, Vongvanij posted five birdies in a bogey-free round.
'I just tried to play two solid rounds and make my way into match play,' Vongvanij said. 'I happened to play really well and I'm happy with that. I was focusing on hitting greens. When I hit it close, I made the birdie, but if not, I lagged it up for a two-putt. I'm going to stick with that game plan.'
Rickie Fowler and Philip Francis ended tied for second place in stroke play at minus-7, while Corey Nagy was 5-under-par.
Kevin Tway also advanced with a two-day score of 1-under.
Winners of this prestigious event reads like a who's who of superstars, starting with none other than Tiger Woods. Ranked as the number one player in the world, Woods captured three consecutive Junior Amateur Championships from 1991-93. Other prominent past winners of this event are: Gay Brewer, Johnny Miller, Gary Koch, Jack Renner, Willie Wood, Brett Quigley and David Duval.