Suzann Pettersen shot a 7-under 65 to share a two-stroke lead with Inbee Park of South Korea halfway through the Taiwan Championship on Friday.
They were at 10-under 134 at the Sunrise Golf and Country Club.
Defending champion Yani Tseng (69), the local favorite, slipped into a tie for third with Catriona Matthew of Scotland (66).
Pettersen, who won in South Korea last weekend beating Matthew in a playoff, recorded seven birdies, four on her last six holes, to catch first-round leader Park.
Park, shot a 69, sank four successive birdies to reach 10 under after nine holes, bogeyed the 17th but reclaimed the lead with a birdie on the last.
Matthew started better than she finished, while Tseng struggled to get going after a bogey on the seventh, managing birdies only on Nos. 13 and 18 to stay in contention.