SOUTHPORT, England — Mo Martin hit the best shot of her life, and it made her a major champion Sunday in the Women’s British Open.

From the middle of the fairway on the par-5 18th hole at Royal Birkdale, Martin ripped a 3-wood that she first thought was too short, and then worried might be too long. It turned out to be close to perfect. The ball hit the middle of the pin and settled 6 feet away for an eagle.

An hour later, that turned out to be the winning shot for the 31-year-old American when Inbee Park and Shanshan Feng could not stay under par.

“I think I still need to be pinched,” Martin said.

A strong wind finally arrived off the Irish Sea, bringing an air of unpredictability to the final round of the Ricoh Women’s British Open.

But this was the topper.

Martin is among the shortest hitters in the game, and won with an eagle – her first of the year. It took her six years just to reach the LPGA Tour, and her first victory in her 64th tournament came in a major championship. She closed with an even-par 72 on a day so tough that no one broke par.

Martin was the only player to break par for the championship, finishing at 1-under 287 for a one-shot victory over Feng and Suzann Pettersen.

Feng made eight straight pars and had the outright lead until she made bogey on the 16th hole. Needing a birdie on one of the two closing holes at Royal Birkdale, which are both par 5s, Feng missed chances of about 15 feet and 10 feet. She shot 75.

Park, who started the day with a one-shot lead in her quest to become the seventh woman to capture four of the LPGA’s majors, fell out of the lead with a bogey on the par-3 14th hole She missed a 12-foot birdie putt on the 17th, then put her tee shot into the right rough on the easy 18th hole and made bogey for a 77.