Garrett, the 2006 Ladies European Tour rookie of the year and winner of back-to-back tournaments last year in Spain, had two birdies on the back nine at Royal Pines.
Her eagle came on the par-five 5th when her sand wedge from more than 118 feet checked on the green and rolled the final 33 feet into the cup.
The large group one stroke back with 68s were England's Lisa Hall and Johanna Head, Taiwan's Tseng Ya-ni, Australia's Kristie Smith, Shani Waugh, Leah Hart, Stephanie Na and Vicky Thomas, South Korea's Shin Hyun-ju and Spain's Tania Elosegui.
Smith, an amateur and daughter of former Australian pro Wayne Smith, upstaged the two other players in her group Friday. Six-time Masters champion Karrie Webb and 2006 winner Amy Yang of South Korea both shot 69s to be in a group of 14 two strokes back that included Americans Carri Wood and Diana D'Alessio.
The tournament was reduced to 54 holes after rain washed out Thursday's first round. A 36-hole cut will be made after Saturday's second round, with the top 65 players and ties advancing to Sunday's final round.
'After all the rain the course has had in the last week, it's not really that wet out there and the greens are perfect,' said Garrett, who was in the first group of the day. 'I was pretty relaxed going out there. I like the 6:40 (a.m.) tee-off. It was a great way to start the tournament.'
Garrett was playing in the same group as three-time former champion Laura Davies of England and South Korea's Shin Ji-yai, who lost in a playoff last week to Webb in the Australian Open at Melbourne's Kingston Heath.
Davies and Shin Ji-yai, who was second to Webb here last year, each had 70s, as did Japanese star Ai Miyazato.
Webb, who also started her round on the 10th, had two bogeys and two birdies in her opening nine but had a run of four straight birdies from holes 2 through 5 before bogeying No. 7.
She was in danger of doing the same on the par-four 8th when her tee shot went into trees on the right side of the fairway. But Webb hit a low 4-iron under a tree and onto the green to about 15 feet and two-putted for par.
'I always feel like the front nine is where you can make your score,' Webb said. 'I didn't play all that well on my first nine -- it was pretty ugly -- and I thought if I could get three or four in the bag, I'd be on my way.'
Smith, who plans to turn professional later this year and will attempt to get her LPGA Tour card for 2009, has had a stomach virus for about a week and was happy to have an extra day to recover when Thursday's round was canceled.
She was also unable to practice early in the week due to heavy rain.
'I haven't been feeling well the past couple of days, so this is a bonus really,' Smith said. 'It's been a very unusual week -- I've been here since Sunday and I haven't seen the course until Friday.'
Yang, who recently graduated from high school on the Gold Coast after moving to Australia from South Korea three years ago, was 5-under with four holes to play when she took a quadruple-bogey 8 on the 6th hole.
After going in the water with her approach shot, her problems continued on the green when she missed a tap-in of about four inches for a three-putt.
Miyazato, who finished second to Webb at Royal Pines in 2005 by one stroke, started on the back nine, bogeying the par-three 11th and getting a birdie on the par-three 16th before three birdies and a bogey on the front.