Eagles at the 18th from Taiwan's Yani Tseng and Australia's Katherine Hull meant they shared the lead at the end of the first day of the Ricoh Women's British Open at Royal Birkdale.
Twenty-one-year-old Tseng had been having a steady round and found herself one under par, without dropping a shot, through 16 holes.
But she then birdied the first of the closing par fives, and followed that up with the eagle which saw her overhaul a group of four players on three under par.
Hull joined her at the top of the leaderboard with a three of her own at the last as she completed her round late in the day.
The chasing group included France's Anne-Lise Caudel, who recovered well after bogeying the first, Korea's Amy Yang and Sun Young-yoo, as well as America's Brittany Lincicome.
Lincicome had looked set for a tough day when she dropped three shots on the first two holes, but responded with six birdies over the remainder of her round.
American Michelle Wie replicated Tseng's birdie-eagle finish to round off the day on two under, where she was joined by In-Kyung Kim.
Ireland's Rebecca Coakley and Martina Gillen were five-over and seven-over after their opening rounds.
England's Laura Davies and Scotland's Janice Moodie were the leading contenders from the UK, ending the day as part of a large group at level par.
Vikki Laing, another Scot, and Becky Brewerton of Wales were at one over.
