SINGAPORE: Former world number one Lydia Ko laboured to joint 27th place with a one-under 71 after the first round of the HSBC Women’s World Championship in Singapore Thursday as the world’s top players struggled to find control under Singapore’s signature sultry conditions.

Unheralded American Jennifer Song took the lead with a seven-under par 65 at the end of day one with China’s world number one Feng Shanshan left five strokes behind on two-under par.