With the match all square at the par-4 18th, Potter executed a masterful shot from the left greenside bunker to save par, and when Shirley’s birdie putt came up a few inches short, it was on to extra holes. After Shirley sent her approach at the 19th hole into the creek fronting the green, Potter lagged her putt to 6 inches and claimed the championship title.

“It feels incredible,” said Potter, a 2011 graduate of the University of Missouri and a professional event coordinator. “I think it's anybody who plays competitive golf's goal to win a USGA championship, and to be able to do it and to do it here at Biltmore Forest, it means the world to me.”

“I played some of the best golf I’ve ever played,” said Shirley, a 2008 Auburn University alumna who works for Atlanta Junior Golf. “It just didn’t end the way I wanted it to.”

Potter became just the third stroke-play medalist in championship history to claim the title, joining Carol Semple Thompson (1990) and Ellen Port (2000). Potter, who turns 26 on Oct. 20, also became the second-youngest winner in championship history, following Sarah LeBrun Ingram in 1991.

The 2013 U.S. Women’s Mid-Amateur Championship is open to female amateur golfers who have reached their 25th birthday by Oct. 5, and is one of 13 national championships conducted annually by the United States Golf Association, 10 of which are strictly for amateurs.

Potter took a 1-up lead with a conceded birdie at the par-3 third. But Shirley chipped within 4 feet at the par-4 fourth, and took the hole with a par to square the match.

Shirley took her first lead of the match at the par-4 fifth, as Potter missed a 6-footer for par, and Shirley converted her 4-foot par putt. Shirley carried a 1-up lead to the inward nine, but Potter squared the match after making a beautiful approach to the par-4 11th.

“I thought I had hit it over (the green), actually,” said Potter, who stuck the approach to 3 feet and was conceded the birdie when Shirley three-putted for bogey. “I think the wind was more in my face than I thought it would be, and it stayed, which I was really lucky. It was probably one of the best shots I had all day.”

The back-and-forth battle continued to the 17th hole with Shirley holding a 1-up lead. Potter found the fairway off the tee for the first time in the championship, and put her approach just off the front of the green, while Shirley reached the green, 35 feet away.

“Funny thing is, I don't really like chipping with my pitching wedge or my 9‑iron,” said Potter. “But I sat there and I was like, no, I really need to take a 9‑iron and bump‑and‑run it back there.”

Potter again displayed her stellar short game, sending her chip within 3 feet of the hole. Shirley left herself 4 feet for par, and when her putt burned the left edge, the match went to 18 all square.

For the second consecutive hole, Potter was saved by her deft short game. With Shirley safely on the green in two, Potter’s approach got caught in the wind and landed in the left greenside bunker, leaving her with a difficult, short-sided shot.

“I had a good lie in that bunker, and I was actually hitting uphill and into the wind, so I knew that would help stop the ball,” said Potter. “All I needed to do was land it on the fringe or just on the green and let it trickle down, and that's what it did.”

Potter’s skillful blast to within 1 foot left Shirley with a birdie putt to win from 15 feet, but she left it just inches shy of the hole.

“I hit a great shot into 18,” said Shirley, “but I couldn’t get too cute with that birdie putt.”

The 19th hole brought back memories of Shirley’s 19-hole semifinal victory over Meghan Stasi, when Stasi stubbed her approach and found the creek fronting the first green. From almost the same location as Stasi, Shirley committed the same mistake, opening the door for Potter to complete the remarkable comeback.

“I had an awkward yardage (64 yards) with a front hole location,” said Shirley, who was competing in her second U.S. Women’s Mid-Amateur. “Going long on that hole is no bargain, either, but the downslope got me.”

“I wasn't watching a lot of Margaret's shots at the end, just kind of basing it off the reaction,” said Potter, who won the hole and the match when Shirley conceded her short par putt. “I heard the shot and then I heard the reaction, and I knew it happened, and I felt awful for her. That's really not how you want to win, and we had played such an incredible match up until that point.”

Potter captured her first USGA title in just her second USGA championship, having fallen in the second round of match play at the 2008 U.S. Women’s Amateur Championship. Potter estimated that she has attempted to qualify for USGA championships 20 times, but never gave up on her goal of taking a championship title.

“I think (this win) speaks to anybody, you just have to keep trying,” said Potter, who had her father, Phil, on the bag throughout the week. “You just never know when you're going to find that course or that week that everything is just kind of working for you like I did this week.”

Potter is the first left-handed female player to capture a USGA championship, and only the sixth left-handed champion in USGA history. She joins Ralph Howe III (1988 U.S. Amateur Public Links), Phil Mickelson (1990 U.S. Amateur), Brian Harman (2003 U.S. Junior Amateur), Cory Whitsett (2007 U.S. Junior Amateur) and Brad Benjamin (2009 U.S. Amateur Public Links).

This was only the third time in championship history that the final match included two players in their 20s, including the 1993 and 1994 finals. It was also the third time that the championship required extra holes, following the 1989 and 1992 finals.

Potter receives a 10-year exemption in the U.S. Women’s Mid-Amateur, while Shirley receives a three-year exemption. Both players are also exempt into the 2014 U.S. Women’s Amateur Championship, which will be conducted at Nassau Country Club in Glen Cove, N.Y., as well as the 2014 U.S. Women’s Amateur Public Links Championship (if otherwise eligible) at The Home Course in DuPont, Wash. The 2014 U.S. Women’s Mid-Amateur Championship will be conducted at Harbour Trees Golf Club in Noblesville, Ind.