RANCHO MIRAGE, Calif. - Lexi Thompson birdied the final hole for a 4-under 68 and the clubhouse lead Friday halfway through the second round of the ANA Inspiration.

The 21-year-old American holed a 30-foot putt on the par-5 18th to reach 7 under at Mission Hills in the LPGA Tour's first major championship of the year. She won the event in 2014, relying on the power game that helped her escape trouble Friday when she strayed into the thick rough.

"If you're going to hit it crooked out here, you might as well hit it far and crooked, so you have a shorter shot in," Thompson said. "But it's very thick. I had some really nasty lies out there. You have to recover, play it smart and roll it up to the openings on the greens."

She's using a new big-headed putter and has scrapped her eyes-closed routine and narrowed her stance.

"It's a dramatic change," Thompson said. "Just changing to the Cure putter and a little bit different stance over the putts has given me a lot of confidence. I'm rolling it a lot better, and having my caddie, Benji (Thompson, no relation), line me up has helped me out a lot, too."

She won in Thailand in February for her seventh tour title.

South Korean players In Gee Chun and Sung Hyun Park were a stroke back along with Lizette Salas.

Chun shot her second straight 69 in her return from a back injury that sidelined her for a month. The U.S. Women's Open champion was hurt when she was struck by a hard-case suitcase that rival player Ha Na Jang's father dropped down an escalator at the Singapore airport.

"During the time I had injury treatments back in Korea, I was so depressed and I lost my appetite and motivation," Chun said. "Once I got here, I began to get my motivation back. ... I'm thankful for the fact that I'm playing again in a major on a big stage."

Salas and Park shot 67. Salas, a former University of Southern California player from Azusa in the Los Angeles area, had a large vocal gallery packed with family and friends.

"They're definitely a huge support whether I'm playing poorly or whether I'm playing awesome," Salas said. "Just having them out here keeps the adrenaline going."

Ai Miyazato, tied for the first-round lead with Azahara Munoz at 67, was playing in the afternoon. Munoz dropped back with a 78.

Hamilton's Alena Sharp was seven strokes behind Thompson after a 74. Brooke Henderson of Smiths Falls, Ont., who opened with a 73, had a late tee time.

Jang was 5 under after a 70. She bogeyed the final hole after a poor drive.

"It was a really big miss off the tee," said Jang, a two-time winner this year. "It's OK. There are two more days. It's no problem."

Stacy Lewis had a 68 to reach 4 under. She won the event in 2011.

Defending champion Brittany Lincicome, paired with Thompson, was 3 under after a 69. Last year, Lincicome eagled the final hole of regulation and beat Lewis on the third hole of a playoff. Lincicome also won the 2009 event.

Top-ranked Lydia Ko and Michelle Wie were in the afternoon group. They each shot 70 on Thursday. The 18-year-old Ko is coming off a victory Sunday in the Kia Classic in Carlsbad.