Lorena Ochoa, battling Jiyai Shin for LPGA Player of the Year honors, fired a first-round 66 on Thursday to hold a one-shot lead in the LPGA's season-ending Tour Championship.

Ochoa was one shot in front of Reilley Rankin, and nothing at the top was set to change when the four groups who failed to finish because of darkness returned to complete their rounds on Friday morning.

Shin, the South Korean who has already wrapped up Rookie of the Year honors and brought an eight-point lead over Ochoa in the Player of the Year race into the tournament, carded a 70.

American Michelle Wie, fresh from her first professional triumph at the Ochoa-hosted LPGA event in Mexico last week, was hampered by a sprained left ankle as she shot a 72.

Wie, who first hurt her ankle at the Solheim Cup in August, went for treatment but later withdrew from the event.

Wie drew the biggest crowds at the Houstonian Golf and Country Club. She was three-under through 12, then her ankle began to give her trouble, especially affecting her on the tee.

"I want to make sure that I'm being smart with it," Wie said. "I will return home to have it looked at by my doctors and follow their advice for treatment."

Her departure put the spotlight firmly on Ochoa and her battle for a fourth straight Player of the Year award.

To earn it, Ochoa must win this week or finish no worse than third and hope Shin places out of the top 10.

Shin and Ochoa both started on the back nine and both were two-under through three. Shin added birdies 13 and 15 to move to get to four-under.

Both players bogeyed the difficult 17th, then picked up birdies early on their second nines. Ochoa nabbed birdies at six, eight and nine, her closing birdie prompting a restrained fist pump.

"Tomorrow is a new start," Ochoa said. "I'm going to play like I'm a few shots behind and continue being aggressive and give myself chances to win on Sunday."

Ochoa is feeling more relaxed this week after dealing with the demands of playing the tournament host at Guadalajara last week.

"Last week was a little bit tough in many different ways with all the things to do and all the pressure," she said. "Everything is a little bit easier, if you compare it to last week."

Ochoa teed off early and was done before afternoon winds picked up.

Shin bogeyed two of her last four holes as the wind strengthened.

"I played two-under, which was not bad in the wind," Shin said. "Lorena, she played really good, a 66. But we still have three more rounds. I will just focus on my game and try my best for three more days."

Shin is trying to become just the second player, after LPGA legend Nancy Lopez in 1978, to win both Rookie of the Year and Player of the Year.

Shin and Ochoa are also in a virtual tie for the Vare Trophy for lowest scoring average.

Rankin also teed off early and finished her 67 before the wind became a factor.

Rankin is looking to put a positive finish on a season in which she missed seven cuts in 17 starts. Her round on Thursday matched her best of the year.

"It was nothing spectacular," she said. "I just tried to stay patient and not worry about how I hit it. I'm just giving myself chances and not getting too frustrated.