Teen star Lydia Ko birdied five straight holes on the back nine to take a one-stroke lead after the third round of the season-opening LPGA Tour's Coates Golf Championship on Friday.

The 17-year-old from New Zealand is a shot ahead of rookie Jang Ha-Na and could become the youngest male or female player ever to reach number one in the world rankings with a victory on Saturday.

"I have been putting good the last few days. I just have to stay in that mood," Ko said.

Ko, who finished 54 holes at 14-under 202, has five career LPGA Tour wins with three of those coming last year.

Jang, the second-round leader, posted a one-under 71 at Golden Ocala Golf course in Florida and is alone in second place at 13-under.

Choi Na-Yeon, another South Korean, carded a six-under 66 to jump into third place at 12-under-par 204.

American Stacy Lewis shot two-under 70 for the second straight round and the world number three is alone in fourth at 10-under 206.

Amy Yang equalled Ko's 65 and jumped into a share of fifth at nine-under. Yang was joined there by Jessica Korda (69) and Austin Ernst (70).

Ko had a strong front nine with four birdies. But she began the back nine with back-to-back bogeys before catching fire and then surging to five straight birdies. She closed with two pars.

"I was kind of shocked," Ko said of the bogeys. "But it got me fired up. I jammed my putter in the bag and said, 'You've got to start working again,' and I made good birdies on 12 to 16."

Ko said she plans to manage her game in Saturday's final round and not think about what others are doing.

"There are so many great players one to four shots back and you just never know what's going to happen," she said.  

"I'm just going to concentrate on my game, just stay really positive, and if somebody else shoots a much better score than I do, I can't really do much about it."

Ask about the possibility of becoming the youngest No. 1, Ko said: "It would be great and it would be a huge honour to be in that position, but we've still got another long 18 holes to go and you just never know what's going to happen in those holes."

Ko said she can always hear her father shouting encouragement from the sidelines and this round was no different.

"I told my dad, 'Dad, the only crowd voice I can hear is you saying like, 'Nice, Lydia.'

"I can always spot it. It's a voice I always hear. And he actually has quite a loud voice just even talking, so he's always verbal out there.

"When there's like no one and my dad does it, I'm like, 'Oh, there goes my dad.'

"But in a way it's good, it kind of gives me a little bit of oomph and it's good to have the support."