Mamiko Higa of Japan leads U.S. Women's Open in her debut at the event

CHARLESTON, S.C. – Japan's Mamiko Higa said she wasn't nervous holding the first-round lead at the U.S. Women's Open. Now she's given her nerves a much bigger test: She holds the second-round lead.

Higa shot an even-par 71 Friday to maintain her edge in her first appearance at the U.S. Open. She rallied with three birdies on her final six holes.

Higa, a 25-year-old known as part of a Japanese sports power couple with sumo wrestler husband Ikioi Shota, wasn't worried after her opening surprise 65, the lowest debut round in tournament history.

"I didn't feel that much pressure," she said through an interpreter.

Higa first dealt with a rain delay of 1 hour, 58 minutes that included a massive lightning strike on a large tree alongside the 18th fairway, unleashing a boom that sounded like an explosion.

Higa trailed Jessica Korda by a shot until she rolled in an 11-foot putt on No. 4, her 13th hole of the day. She followed with two more birdies, the last of them on a 14-foot putt on No. 9.

Darkness was closing in when she holed that final birdie.

There were 45 players still on the course when the horn sounded. They'll return Saturday to finish before the third round starts. The tournament announced players will go off in threesomes to ensure getting the round in.

Korda shot a 68, her lowest score in 38 rounds in the U.S. Open.

American amateur Gina Kim had a 72 to join Celine Boutier of France at 4 under. Boutier had four holes to play.