Sherri Steinhauer, who bested Lorie Kane in a playoff to capture this event in 1999, carded a 2-under-par 69 to finish alongside Kelli Kuehne, Kris Tschetter and Silvia Cavalleri.
Marshall started on the back side at Wykagyl Country Club and picked up her first birdie of the day at the 11th when she knocked her 9-iron inside two feet. She two-putted for birdie at the par-5 18th and reach 3-under with a birdie at the second.
At the par-3 fourth, Marshall hit a 5-wood off the tee and dropped the ball within eight feet of the cup. She drained the putt for birdie and the outright lead at 4-under.
Marshall seemed in control until late in her round. She missed a five-foot par save at the seventh and added another bogey at the eighth after she couldn't get up and down to fall one back of Yeo.
Marshall responded at the very next hole. She hit a brilliant second shot inside two feet for birdie and a share of first.
'That was huge. I'll definitely sleep better tonight,' said the 35-year-old. 'I watch the scoreboard all the time, and I knew I was leading at 4-under and that seven is a tough hole. If you don't hit the fairways, you can definitely make bogeys. So it was good to comeback and be joint leader after I almost let it slip away.'
Marshall has one victory on the LPGA Tour, the 1995 Jamie Farr Toledo Classic. She has yet to post a top-10 finish in 2002 and has missed the cut in her last four appearances.
'I had a really good stretch until Evian,' said Marshall. 'Then my husband and I were discussing whether or not to take a week off. We decided to keep going, and that was the worst mistake we ever made. I missed four cuts in a row. The last one, I missed by one and I thought we were in. So it's been a tough last month.'
Yeo took the early lead with five birdies and two bogeys. She also used a birdie at her closing hole, the 18th, to assure a share of the lead. After she sent her drive into heavy rough, Yeo hit a 7-wood out and chipped to seven feet to finish at 3-under.
Yeo, who turned pro in 2000, missed the cut at this event last year. She had a disappointing season in 2001 but retained her card after she finished tied for 31st at the LPGA Final Qualifying School.
'I wasn't ready mentally,' said the Korean. 'I was always a good player in high school, college and the mini-tour, but I tried too hard to make it happen. I learned from last year's Q-School to let it happen.'
Karrie Webb managed five birdies and four bogeys to finish two shots off the pace at 1-under-par 70. She was joined by Michelle Bell, Stephanie Keever, Meg Mallon, Hee-Won Han, Leta Lindley, Jenny Rosales, Beth Bauer, Candie Kung and Joan Pitcock in a tie for seventh.
Annika Sorenstam, a two-time winner of this event, finished three shots back after a round of even-par 72.
Defending champion Rosie Jones, who has earned five of her 12 career victories in the state of New York, struggled to a round of 4-over-par 75 alongside Juli Inkster, who is making her first start since her second U.S. Women's Open title.
Full-field scores from the Sybase Big Apple Classic