Lydia Ko's kept within touching distance of the lead despite not moving spots after a three under par 68 second round at the LPGA Classic in Michigan.

The world number one remains in a share of 13th, three shots off the lead at seven under for the tournament.

Ko followed her opening-round 67 with a three-under 68 to hit the halfway point at Blythefield Country Club tied for 13th on seven under, just three shots off the pace set by Canada's Alena Sharp on 10 under, with four holes to play.

South Korea's Q Baek, In Gee Chun and So Yeon Ryu, American Lexi Thompson and England's Jodi Ewart Shadoff are all a shot back of the lead on nine under.