NAPLES, Fla. — Angel Yin rammed in a 30-foot par putt on her opening hole, setting the tone for a day of big putts and a 3-under 69 that gave her a two-shot lead Friday in the CME Group Tour Championship and the chase for the $4 million prize.

Very clear in her rearview mirror was Nelly Korda.

Korda, coming off her seventh win of the season last week, opened with a 72 and was eight shots behind. She found a simple swing thought after the round and was back to her old self with a 66 that cut the deficit in half with 36 holes left to play.

“Golf is just crazy,” Korda said. “You go from playing so well last week to not being able to find the center of the clubface yesterday. Always humbles you, but that’s what you love so much about it. Went to the range after my round yesterday. Tried to find a different feel. Felt a little better out there today, and hopefully I can keep progressing.”

Yin followed that 30-foot par putt with a 40-foot birdie putt on the next hole. She also holed a birdie putt from about 35 feet on the 11th hole that put her in the lead for good.

She was at 10-under 134. Hye-Jin Choi (68) and Narin An (72) were 8 under.

Korda, who already has captured her first award as player of the year, was tied for fourth at 138 with four other players who are either major champions or have been No. 1 in the women’s world ranking — Jeeno Thitikul, Ayaka Furue, Ruoning Yin and Amy Yang, the defending champion at Tiburon Golf Club.

Furue also is in a tight battle for the Vare Trophy for the lowest scoring average, and she pulled to within a fraction of a point of Haeran Ryu.

Yin’s round had enough bogeys to slow her momentum, along with a discussion with a rules official over where she took her drop after going in the water on the par-3 fourth hole.

“It looked like I took an improper drop where I went up closer than I should have, where I should have dropped further back,” said Yin, who was asked to review footage. “They thought I didn’t take the drop properly. I explained to them that I believe I did take the drop properly.”

She said it was discussed with everyone in her group. She said a marshal never volunteered any information. The drop stood, she took bogey and was moving on.

“I believe my drop was right,” Yin said.

Korda, meanwhile, grazed the cup with birdie chances and then made it up for it on the third hole when her 8-iron from the rough landed so perfectly that it rolled into the cup for an eagle. That sent her on her way.

The key to getting her game on track was more hinge in taking the club away and taking a shorter swing. It all came together. Korda also said she finally was able to get some rest after a busy week of awards.

Yin won $1 million last year in the Aon Risk-Reward Challenge, a bonus competition all year that measures how players fare on holes that have risk, such as a reachable par 5. That $1 million meant a lot to her, and she said it gave her some financial freedom.

What would $4 million mean?

“Even bigger financial freedom,” she said.