Ko carded a four-under round of 68 at the Sentosa Golf Course on Thursday to lie two shots off the pace of co-leaders Inbee Park and Yani Tseng.
It was hardly a shameful performance from the teenager, but she looked a bit flat and struggled in hot conditions. Having arrived in Singapore from New Zealand earlier in the week, Ko was still adjusting after her flight.
"Yeah I’m tired. A little bit jetlagged because of the long flight," the New Zealander told reporters.
"But I’ve been trying to pace myself, go nine holes and do the least amount of practice."
The South Korea-born Ko is bidding to win her third title in three weeks, having all ready triumphed this year at the New Zealand Open and the Australian Open.