The 21-year-old from Thailand was in danger of losing momentum at Mission Hills Country Club, following a 10-hole stretch where she made two bogeys and could not pick up any strokes, but rebounded to finish the last four holes three under par and move to nine under for the tournament.

Feng Shanshan remains one shot behind but is now in second place outright after she too shot 69.

China's Feng also ended round two strongly, in her case with birdies on 17 and 18.

Tavatanakit's compatriot Moriya Jutanugarn is third, two shots off the lead, after she too shot 69.

England's Charley Hull - another who produced a second-round 69 - and Swede Anna Nordqvist are six under par.

The leader is outside the top 100 in the world rankings and inexperienced at this level, having only made a Ladies Professional Golf Association Tour debut in 2020.

Feng and Nordqvist are both previous major winners, by comparison.

Tavatanakit put some further distance between herself and much of the chasing pack on day two, but a formidable group of players is four shots off the pace.

Olympic champion Park Inbee, defending champion Lee Mi-rim and world number one Ko Jin-young - all of South Korea - are each on five under par.

New Zealand's Lydia Ko - a two-time major winner and ex-world number one - plus Germany's British Open champion Sophia Popov and Georgia Hall of England are also tied for sixth place.

Seventy-one players made the cut, with two more rounds scheduled at the first women's major of the year.