The 2019 KPMG Women's PGA Championship winner fired an opening six-under 66 to be just two off leader Jeongeun Lee6 in the tournament which carries prizemoney of US$1.5 million.

Earlier in the week, Green's attacking prowess and ability to maximise opportunities on the carefully-selected holes used at each LPGA event propelled her to 29-under-par to win the Challenge.

The 24-year-old from Perth was again rewarded for her aggression again when she birdied the first, second, sixth, eighth, 11th, 14th and 17th holes at the Tiburon Golf Club on Thursday.

Her only blemish came at the par-3 16th, where she made bogey.

Hannah Green once again was rewarded for her aggressive play on day one of the CME Group Tour Championship. PHOTO: Michael Reaves/Getty Images.

Joining her on 66 is compatriot Minjee Lee, who had an astonishing birdie run from the third hole to the ninth interrupted by a bogey on six.

The World No.7 mixed two more birdies on 10 and 13 with a bogey on 14, to be tied sixth in a large group that also includes Nelly Korda, Yuka Saso and So Yeon Ryu.

Lee6's opening 64 was bogey-free and earned her a one-stroke lead over South Korea's Sei Young Kim, France's Celine Boutier and Americans Jennifer Kupcho and Mina Harigae.

The field of 60 was determined via the LPGA Tour's season-long points race. Now the points are reset and all 60 players have a chance to win the US$1.5 million first prize and the Race to the CME Globe crown.

Five of Lee6's eight birdies came on the back nine, including each of her final three holes. She drained a lengthy putt for birdie at the par-3 16th hole.

"My feel is getting better, so my goal is to win once this year, but unfortunate just one tournament left," Lee6 said. "Yeah, I'm going to try my best."