Angel Yin avoided a penalty to fire a three-under par 69 and grab a two-stroke lead while top-ranked Nelly Korda jumped into contention after the second round of the LPGA Tour Championship.

Yin, a 26-year-old American, made six birdies, three bogeys and clutch par putts on the last two holes in windy conditions to stand on 10-under 134 after 36 holes at Tiburon Golf Club in Naples, Florida.

Her score withstood a penalty inquiry as after the round, LPGA rules officials told Yin of a possible violation for an improper drop on the fourth hole.

Yin’s second shot at the fourth hole, where she made a bogey, went into the water. She looked for the ball on a slope near the green where she thought it might have landed.

“They wanted to ask me about the process of the drop and if I used all my resources to come to a determination of where I crossed (the water hazard) and took my drop,” Yin said.

“It looked like I took an improper drop where I went up closer than I should have. They thought I didn’t take the drop properly.”

“I explained to them I believe I did take the drop properly. I asked everybody and everybody was in agreement. I told them how I hit the shot, where it flew, and that’s where I came to the determination of where I dropped.”

“We just had to clarify it,” Yin said.

“Everybody is trying to do their best. I don’t think it’s anything with anyone. Everyone is trying to hold up integrity.”

South Korea’s Choi Hye-jin fired a bogey-free 68 to share second on 136 with compatriot An Na-rin, the first-day leader after an opening 64.

The top 60 players in the season points chase qualified for the $11 million showdown, which offers a $4 million top prize.

Yin, ranked 34th, won her only LPGA title last year at Shanghai.

She birdied the second hole but then made back-to-back bogeys at three and four. She answered with birdies at the par-5 sixth and par-4 ninth then added birdies at 11, 13, 15.

Yin lipped out an 18-foot par putt to bogey 16 but sank tense six-foot par putts at 17 and 18 to keep her lead, even after the penalty scare.