After fending off Christopher Deforest 3 and 1 in the second round, Tway downed Jean-Philippe Paiement 3 and 2 in round three to moves into the quarters. Tway will battle Wesley Graham, a 1-up winner over Drew Kittleson.
Danny Lee will face Richard Lee in the quarterfinals Friday. Danny bested Robbie Ziegler, 1-up, while Richard took down Cody Gribble by a 3 and 2 margin.
Philip Francis held off Morgan Hoffman for a 1-up win. Francis advances to play Sihwan Kim, who defeated John Douglas Archibald, 3 and 2.
The last quarterfinal match will feature Andrew Putnam and William Cauley. Putnam beat Tadd Fujikawa, 3 and 2, while Cauley downed Steve Ziegler 3 and 1. Fujikawa was the youngest player to ever qualify for the U.S. Open when he did so earlier this year. However, he missed the cut at Winged Foot.
Tway, the 17-year-old son of PGA TOUR winner Bob Tway, was 2-down after two holes at Rancho Santa Fe Golf Club and he did not even the match until making a birdie on the ninth.
After he and Paiement parred the 10th, Tway birdied two of the next three holes. Paiement bogeyed the 14th and was knocked out of the event as the pair halved the next two with pars.
Graham and Kittleson had a see-saw affair that saw Graham win six holes, while Kittleson won five holes, but it was his bogey on 17 that helped Graham move on.
Danny Lee, who took down medalist Arnond Vongvanij 1-up in round two, never trailed in the afternoon bout with Robbie Ziegler. Lee was 3-up after four holes thanks in part to two Ziegler bogeys.
Ziegler got back within 1-down three different times, but was never able to square the match. After Ziegler won the 14th thanks to Lee's bogey, the duo halved the final four holes with pars allowing Lee to move on.
Richard Lee won three of his first five holes, but Gribble won the other two and Lee's double bogey on the eighth evened the match. It remained that way until Lee birdied the 11th. Lee finished the match with birdies on 15 and 16.
Francis was 2-down after four, but he won five straight holes to take a 3-up lead. Hoffman birdied 15 and 16 to get back to 1-down, but they each parred the final two holes giving Francis the win.
Kim made the turn with a 3-up lead as Archibald was four-over par the opening nine holes. Kim twice pushed his lead to 4-up on the back nine and closed out the match with a par on the 16th.
Putnam won four of five holes from the fifth and cruised from there. Cauley never trailed against Steve Ziegler. Cauley was 1-up around the turn and closed out the match with a birdie on the par-3 17th.