MEXICO CITY — Japan's Chisato Iwai birdied five of the first six holes to seize command on her way to winning the Mexico Riviera Maya Open on Sunday for her first LPGA title.

The 22-year-old from Saitama fired a final-round six-under par 66 to finish 72 holes on 12-under 276 at Mayakoba resort.

She matched the biggest LPGA victory margin this year in defeating runner-up Jenny Bae by six strokes with South Korea's Kang Hae-ji third on 283.

“I'm so happy,” Iwai said. “My mentality was so calm every time. It was just calm, good play.”

Iwai became the third LPGA winner of the season from Japan, after Rio Takeda won the Blue Bell in China in March and Mao Saigo took the Chevron Championship last month, and the 20th Japanese player overall to win an LPGA crown.

Iwai, who won her eighth Japan Tour event in March, earned her LPGA Tour spot with a runner-up showing in last December's qualifying tournament and won as a rookie just five months later.

Dominant early in the final round, Iwai opened with a birdie and reeled off four more in a row starting at the third hole.

"Nervous in the morning, but I played the first hole and I was calmed down," Iwai said.

She added birdies at the par-three 10th and par-five 13th to reach 13-under and stretch her lead to eight strokes.

Bae, a 23-year-old American rookie who began the day with a one-stroke lead over Iwai, opened with back-to-back bogeys, went bogey-birdie at the par-five fifth and par-four sixth and closed the front nine with another bogey to tumble out of contention.

Iwai made her first bogey of the weekend at the 14th hole and Bae made birdies at 13 and the par-three 15th but added a bogey at 17 as Iwai's lead only slid to seven strokes before Bae closed with a birdie.

“I'm pretty happy with this week,” Bae said. “It just tells me that I have a long ways to go but also I'm also getting there, too.”

"I definitely realized that I've gotten more patience. I think that's a really key thing out here, just being able to focus within all the stress and pressure. I think that was really good.”

“So I'm happy. I definitely know what I need to work on for the week off for me. Hopefully I'll be able to score better at the next tournament.”