Lydia Ko has maintained second place at the Swinging Skirts classic in San Francisco despite briefly holding the lead during Sunday's third round.
Ko carded a four under par 68 on day three to be nine under for the tournament, one stroke adrift of the leader from the United States Stacey Lewis.
The New Zealander struck two birdies on the front nine to take the outright lead, but a bogey on the par four 11th dropped her back into a share of first place with Lewis.
The playing partners dueled for the lead on the home ward nine with both hitting birdies on 12, 15 and 16 before Lewis pulled clear with an unanswered birdie on 17.
The American also carded a four under par 68 in the third round to maintain the one stroke advantage she held after day two and will again be paired with Ko in Monday's final round.
Ko is three strokes clear of third placed Jenny Shin of Korea.