Lydia Ko's assured touch with the putter deserted her in the second round of the women's golf tournament at the Rio Olympics to send her sliding down the leaderboard.

The 19-year-old world No.1 managed only two birdies in her round of one-under par 70 to sit seven shots off the lead held by Korea's Inbee Park at 10-under.

Park shot a second successive round of 66 at Marapendi to hold a one shot lead over America's Stacy Lewis who fired an eight-under 63 to move into medal contention.

Ko sits in a share of 22nd and knows her putter has to get hot in Friday's third round for her to be in the reckoning for a medal.


"When you're not holing many putts, it can get a little frustrating.

"I feel like there's still a lot of golf to be played, and I feel like there's a lower number than what I've shot the last two days. Hopefully that's coming in the next two," she said.

Ko had birdied chances on the first six holes but failed to pick up any shots and then dropped a stroke at the seventh.

She picked up shots at 15 and 16 but knows she needs to improve her play on the front nine, where she's been one-over both days, to stand a chance.

"If I put myself in that better position and put less pressure going into the back nine, that's a big key for me the next two days.

"If you start holing putts, you know that you can hole them again and again.

"The big key for me is to go tomorrow and the next day and play those first few holes feeling confident with the putter."