Yip had a chance to win with a par at Merion Golf Club's difficult, par-4 closing hole, but ran that 20-footer 5 feet past the hole. Harman failed to convert an 8-footer for bogey, then Yip sank his bogey putt to win 1-up and move on to face Dillon Dougherty in Friday's quarterfinal.
'You can understand why Tiger Woods counts this as a major victory, because this feels like a major out here with all of the people around,' said Yip, who carries his own bag. 'It really feels like a major atmosphere, and I've been to a major tournament before watching. You kind of get that feeling out there, just trying to grind your way around and make pars, that's what major championships are about, just making pars.'
Dougherty advanced thanks to a 2-and-1 victory over Dane Burkhart on Thursday. Burkhart knocked off medalist and NCAA Individual Champion, James Lepp in Thursday's second-round match.
Mark Leon holed a 35-foot putt on 18 to win 1-up against Kevin Chappell. Leon will now take on J.C. Deacon on Friday after Deacon ousted the 52-year-old George Zahringer, 1-up.
Dawie Van der Walt of South Africa destroyed Korey Mahoney, 5 and 4, in the third round. He will meet Italy's Edoardo Molinari, who was a 3-and-2 victor over Matthew Swan.
Anthony Kim birdied the first extra hole on Thursday to best Jay Choi, 1-up. Kim will face Austin Eaton III in the quarterfinals. Eaton benefited when Rhys Davies bogeyed the 16th and Eaton held on for the 1-up win.
The quarterfinals are on tap Friday with the semifinals Saturday. The 36-hole final will be played Sunday.