Lydia Ko has produced an incredible back-nine to grab a share of the lead at this week's LPGA Tour event in Arkansas.

The world number one has carded a 28, with five birdies and an eagle on the last, to rise from seven-under par mid-way through her second round to be 14-under par for the tournament.

It's the lowest nine hole score this season and Ko's nine-under 62 equals the tournament record.

Ko's tied for the lead with American Morgan Pressell, who earlier shot an eight-under 63.