SYLVANIA, Ohio (AP) -- Not even a sore back could keep Lydia Ko from building a four-shot lead in the Marathon Classic. Now the former No. 1 player in the world is one round away from ending more than two years without a victory.
Ko felt back pain on the front nine, received treatment from a trainer and played bogey-free over the last 15 holes at Highland Meadows for a 3-under 68 and a four-shot lead over Danielle Kang.
''I actually woke up this morning and I felt great. I started hitting some balls on the driving range and felt it a little bit. As I was playing I could feel it a little bit more,'' Ko said. ''I don't have a back injury, so I think this is a one-off thing. There are more important things than the back right now, so I'm just going to go out there tomorrow, even if I do feel it, and just make sure that I'm still swinging aggressively.''
Ko has gone 44 tournaments worldwide since her last victory.
Kang, who won last week at nearby Inverness Club, had a 70 and was four shots behind.
Kang got within two shots of the lead with a birdie on the par-3 14th, but she bogeyed the next and picked up one birdie on the final two holes, both of them par 5s. Ko, meanwhile, birdied the 16th and 17th and finished four ahead.
''Some days your game is all there and some days you just kind of have to make it work and you have new challenges every day,'' Kang said. ''Today my challenge was to get it on the golf course and somehow shoot under par. I think that was my goal, and I think walking away without as big of a damage as I thought I could have made today was a win for me today.''
Ko was at 16-under 197.
She had a one-shot lead going into the third round at Highland Meadows and seized control early, stretching her lead to three shots at the turn. Unlike the opening two rounds, when birdies were required to keep pace, this round was all about pars. Ko ran off nine straight pars until her big finish.
It was shaping up as a two-player race.
Minjee Lee of Australia had a 68, while Jodi Ewart Shadoff, who started the round one shot behind, struggled to a 73. They were at 10-under 203, six shots behind.
''I think tomorrow I'm going to go out there and not try to protect my lead, but go out there and play the best golf I can,'' Ko said.
Lexi Thompson also lost ground with a 73 and fell 12 shots back of Ko.
Ko was heralded as the future of the LPGA Tour when she won the Canadian Women's Open as a 15-year-old amateur. She was 17 when she first rose to No. 1 in the world, and she compiled 14 wins and two majors before turning 20.
But she has only one victory the past four years.
Ko is a two-time winner of the Marathon Classic. A third win could be just what she needs to get back on track.