DALY CITY, Calif. – American Ryann O’Toole’s late charge Friday broke up a leaderboard that looked like a “Who’s Who” of South Korean women’s golf.

O’Toole birdied three of her last four holes to shoot 7-under-par 65 and tie the low round of the Mediheal Championship this week.

“My swing has just been evolving in a great direction, very consistent,” O’Toole said. “I haven't played great this season, but I felt like it's been right there.”

O’Toole is the lone American on a leaderboard dominated by Koreans.

So Yeon Ryu (70) leads at 7 under overall.

Sei Young Kim (66) is tied with O’Toole one shot back.

Inbee Park (69), Na Yeon Choi (67), Eun Hee Ji (72) and He Yong Choi (65) are tied with England’s Charley Hull (70) two shots back.

In Gee Chun (71) and Chella Choi (68) are just three back.

O’Toole, 34, is looking to claim her first LPGA title. She said she’s inspired at Lake Merced. She won a U.S. Women’s Open qualifier here that got her into the 2011 U.S. Women’s Open at Broadmoor, where she tied for ninth. That helped her get on the U.S. Solheim Cup that year.

“I like the way this course sets up,” O’Toole said. “I like more challenging golf courses. Harder, firmer, longer, faster. To me, it's more of a shot-making golf course. And I think it doesn't put the pressure on, like if it's a birdie-fest. I don't think that's ever been really my style of golf.”