Lydia Ko is in a tie for 10th at the halfway mark of the LPGA's CME Group Tour Championship event in Florida.

Ko backed up her first round 71 with another one-under par effort two leave her two-under for the tournament.

The 17-year-old, who yesterday won the LPGA's Rookie of the Year award, started brightly with a birdie on the par-five first, but immediately undid that good work with a bogey on the second.

That theme continued throughout the round, with bogeys on the ninth and 16th holes undermining birdies on the sixth, 11th and 14th.


Despite that, Ko remains in touch with the leaders - Spain's Carlota Ciganda and Paraguay's Julieta Granada, who are tied at seven under.

A win at this tournament could thrust Ko to the top of the LPGA Tour's order of merit - known as the Race to the CME Globe standings. That would net her a NZ$1.89m bonus to add to her $1.7m earnings this season.