The 26-year-old star had the largest gallery of the field following her around the Ginn Reunion Resort, a crowd that helped keep her from feeling completely worn-down after so many rounds without much of a break.
"I'm still a little bit tired," she said. "I wouldn't say it's all the energy that I ever felt, but I'm OK. I think I'm hanging in there. ... If I knew I had maybe two more tournaments coming, I would be crying right now."
Juli Inkster (69), Annika Sorenstam (70) and Morgan Pressel (72) weren't far behind, part of 65 players who shot par or better.
Koch may have been the most unlikely name on the leaderboard.
Sure, she shot a 66 in the final round in Mexico last week and tied for fifth. But that was her best showing since winning her second career event in 2005. She mostly struggled the last two years.
"I'm just really excited right now," she said. "I've had a couple of bad years and I'm finally starting to play solid golf again. I'm hitting a lot of fairways and a lot of greens, so that's what I'm going to focus on rather than what Lorena and Annika are doing.
"It's so much more fun for me to play again now."
Her putting was a big reason Thursday. She made seven putts from 12 feet or longer, including a 20-footer on No. 17 and a 30-footer on 18 for a birdie-birdie finish.
"I'm definitely rolling it good," Koch said. "It's not all luck. There's a lot of good putts. I'm definitely confident on the green right now."
Notes: Ochoa will get next week off and already has plans to have lunch with her family Monday. ... Leta Lindley had the shot of the day, a hole-in-one at No. 12. She holed an 8-iron from 135 yards. ... The par-3 16th was one of the toughest holes, yielding just six birdies and giving out 45 bogeys and five double-bogeys.
