CARLSBAD, Calif. (AP) — Cristie Kerr shot an 8-under 64 on Friday in the Kia Classic to open a five-stroke lead halfway through the second round.

The 40-year-old Kerr, the 2015 winner at Aviara, had eight birdies in her second straight bogey-free round to reach 13-under 131 on the rain-softened course.

“I like winning. I like challenging myself,” Kerr said. “Definitely doesn’t get any easier as you get older with the travel and recovery time. I got up this morning and I’m like, ‘Man, why does my hamstring hurt?’ From working around this hilly golf course. The golf ball doesn’t know an age. I’ve always said that. As long as I stay hungry, going to just keep playing.”

She has 20 LPGA Tour victories, winning twice last year. She also helped the U.S. beat Europe last summer in her ninth Solheim Cup appearance.

“It’s tough as you get older just being fresh and rested,” Kerr said. “I put more focus into that as I’ve gotten older. I still practice, but off the course I try to get more rest.”

Lizette Salas, Hee Young Park and Caroline Hedwall were tied for second. Salas had a 67, and Park and Hedwall shot 70.

“I really like this golf course. I really like the environment,” said Salas, the former University of Southern California player from Azusa. “My family gets to come out. So much confidence at the beginning of the week, and definitely showed the first two days.

The afternoon starters included top-ranked Shanshan Feng, Inbee Park, Michelle Wie, Ariya Jutanugarn and Lydia Ko. Lexi Thompson was 2 over after a 74, leaving her in danger of missing the cut in the final event before the major ANA Inspiration next week at Mission Hills.

Kerr opened with birdies on the par-5 10th and par-3 11th, added birdies on the par-4 16th, 18th and second, and ran off three in a row on the par-3 sixth, par-4 seventh and par-5 eighth.

“I don’t think you can fall asleep on one shot,” Kerr said. “It’s a really good golf course. I think I play better on courses that demand the focus, so I think that’s why I’ve played well here in the past. … I’m trying not to put limits on myself right now. I’ve got some good things going on with my swing.”

She has long been one best putters and green-readers in the world.

“I can see the subtleties that a lot of people can’t,” Kerr said. “It’s a gift from God being able to do that. I’ve always had that, so I’m lucky.”