In the first semifinal match, Yip birdied the second to move 1-up, but Kelly squared the match when Yip bogeyed five. The pair remained all-square until Kelly took the 10th with a birdie.
Kelly captured the 12th thanks to a bogey from Yip. Kelly, now 2-up, squandered a 5-foot chance to put the match away at 16. They halved the hole with bogeys, but when the duo halved the par-3 17th, Kelly moved on to the final.
'I seem like I've been down early and I found a way to kind of scratch and claw my way back, and once I've gotten the lead, I haven't surrendered it,' said Kelly. 'So I played well on the back nine especially.'
For Yip, it is another year and another lost opportunity. In 2005 at Merion Golf Club, Yip made it to the quarterfinals before losing to eventual runner-up Dillon Dougherty.
'I felt like I was in control and I just couldn't pull it through, so it's kind of frustrating,' acknowledged Yip, who suffered a similar fate in last week's Canadian Amateur Championship. 'He was real solid and never made really any mistakes.'
Ramsay won the first hole, then birdied four to go 2-up. The Scotsman got to 3-up with a par at six, but that margin shrunk one hole later when Simpson birdied seven.
Ramsay got back to 3-up with a birdie at the par-five 11th, then Simpson fought back. Simpson won the 12th with par and the 14th with a birdie. Ramsay got back to 2-up with a birdie at 15 and he would need that hole.
For the second day in a row, Ramsay was assessed a penalty. On the 16th, it was ruled that he grounded his club during a practice shot in a hazard. That resulted in a loss of a hole and he was 1-up with two to play.
'I didn't think I grounded my club,' said Ramsay, who was penalized on Friday when his caddie touched his putting line. 'Obviously someone's maybe seen something that showed it to be different.'
They halved 17 with pars, then 18 with bogeys as Ramsay moved on to the final.
Now Ramsay and Kelly will be invited to the Masters and U.S. Open, which is something Ramsay is happy about, but not something he will be dwelling on Sunday.
'I've got to stay focused and all I can think of is tomorrow and playing well,' said Ramsay. 'That's probably got to be put to the back of my mind at the moment.'