A year after losing to Lilia Vu in a play-off, Kim rattled off six birdies and an eagle at the par-5 10th hole in her round of 65 to be outright second behind South Korean Mi Hyang Lee.

All up, five Australians occupy positions inside the top 15 at Blythefield Country Club in Belmont.

Karis Davidson produced a bogey-free 66 to share third with Sofia Garcia of Paraguay.

Dual major winner Minjee Lee and Gabriela Ruffels are a stroke further back in a tie for sixth after opening with 67s.

Fellow Australian Cassie Porter continued her great start to her rookie LPGA Tour season with a 68 to be joint 11th.     

But leader Lee is the woman to catch after the Korean played a six-hole stretch in six under to set a cracking pace in the final event before next week's Women's PGA Championship in Texas.

Cassie Porter is tied for 11th in Michigan. PHOTO: Getty Images.

Only three of the top 10 in the world are competing at the $US3 million tournament. Haeran Ryu, the highest-ranked player at No.5, shot a 69 in the afternoon.

Playing in the morning on the tree-lined course, Lee birdied holes five to eight, parred the ninth and eagled the 10th after surprising herself by reaching the green in two on the par-5 hole.

"I didn't expect I can hit the green there for my second shot," Lee said. "But it was a great line and good hit with the three wood and I made the green. It was almost 24 feet, like right-to left-eagle putt. I didn't expect to make it."

The 32-year-old capped the bogey-free round with further birdies on 14 and 17.

"I missed only two fairways," Lee said. "I think that's a lot of help to hit the greens a lot, too."

Kim chipped in for eagle on 10 and for birdie on 11 in her morning round. 

"That was a good start to the back nine," the Sydneysider said.

"Just kind of saved pars early and then loosened up as we went on. That was quite nice."

Vu opened her title defence with a five-over 77.