Late stumble costs Ko the lead

Lydia Ko is right in the hunt at the CME Group Tour Championship, despite a late stumble in her second round.

The 18-year-old world number one had played herself into the share of the lead on Friday after picking up six birdies in her first 11 holes, but she made a double bogey at the 15th and then another bogey at 16 to drop three shots in the blink of an eye.

Incredibly, it was Ko's first double bogey since 2013, but she was still able to bounce back with closing birdies at 17 and 18 to sign for a five-under-par 67.

That moved her into second place on eight under par, two shots behind South Korea's Ha Na Jang, who shot to the top courtesy of a second-round 65.

Jang has never won on the LPGA Tour, but has been knocking on the door, with three runner-up finishes during 2015.

She made eight birdies on the day, with only a single blemish on her card.

Cristie Kerr and Jennifer Song follow one shot behind Ko, while Karine Icher, Gerina Piller and Brittany Lincicome share fifth place on six under.

Some big names follow on five under, including Lexi Thompson and Ai Miyazato, as well as overnight leader Austin Ernst, who fell down the leaderboard after a disappointing 74. 

Ko's main rival for top honours at the end of the season, Inbee Park, is among a large group on four under par.

Park made her fair share of birdies on the day – three on the front nine and three more on the back – but she also had three bogeys, forcing her to settle for a three-under-par 69.