Five players are one shot back, including Danielle Kang, Gaby Lopez and Lydia Ko, at Aronimink Golf Club in Pennsylvania.

American Lincicome, a two-time major winner, made only one bogey in a round of 67, which included a birdie on the ninth hole - her last of the round.

Lincicome was the ANA Inspiration champion in 2009 and 2015.

Tan, 26, also began her round on the 10th hole and was at four under after nine holes.

The Malaysian has never finished better than in a tie for 30th place at a major before, but is enjoying a good year after regaining her LPGA Tour card.

New Zealand's Ko - another two-time major winner and formerly the world number one, made a bogey on the final hole otherwise she too would have a share of the lead.

Ko finished second at this event in 2016.

Kang, the world number three, reached the turn at three under but lost a shot over the front nine, which she played second.

The Women's PGA Championship winner in 2017, Kang won two LPGA Tour events in August and is one of the most in-form players in Pennsylvania, although missed out on top-10 finishes at both of this year's majors so far.

Cydney Clanton of the United States, Sweden's Linnea Ström, Mexican López and Carlota Ciganda of Spain also shot 68 to be tied for third place.

Olympic champion Park Inbee - a seven-time major winner - is among a host of players on even par, tied for 13th.

American Lexi Thompson, Hinako Shibuno of Japan and England's Charley Hull and Georgia Hall all shot level-par 70s.

Australian Hannah Green, the defending champion, had a horrible opening round and is nine over par.

Lee Mi-rim of South Korea, who won the ANA Inspiration last month, shot a seven-over 77.

The second of four scheduled rounds will be played tomorrow.