Ryu So-Yeon won her first LPGA Tour title in two years after she claimed victory in the Canadian Women's Open title.
The South Korean held off the challenge of Choi Na-Yeon to win her first tournament since the 2012 Toledo Classic.
$337,500 prize money
Ryu earned $337,500 for the win and since her last victory she has had 27 top-10 finishes in 49 events.
The 2011 US Women's Open champion got the better of compatriot Choi with a birdie at the 16th proving crucial as he edged to victory by two strokes.
Ryu admitted that she was just focused on her own game and ignored the challenge from Choi.
"I did trust myself," Ryu said. "I didn't care about anybody else. I focused on my game. I wasn't playing my best game on the back nine but I just kept through it."
While she also felt that the birdie on the 16th was the crucial moment on her way to victory.
"Hole 16 was a really big hole. I was sure if I made (the birdie putt) I was going to win it. I was really happy I made it."
Final round pressure
Choi had applied pressure on Ryu during the final round after a 15-foot birdie on the 15th meaning there was just one shot between the players.
But a birdie-par-par finish saw Ryu match the season-low LPGA 72-hole total as she finished the tournament on 23-under par.
Ryu had begun the tournament with a course record of 63 and with further rounds of 66 and 67 saw her take a four-stroke lead into the final day. At one time during the final day, Ryu had a six-shot advantage but that was quickly reduced when she bogeyed the 15th and Choi birdied it.
Choi admitted that following that two stroke swing she thought she could complete a miraculous turnaround.
"When she missed that putt, I thought, 'Maybe I could have a chance,'" Choi said.
But the birdie for Ryu on the 16th quickly put an end to any hopes Choi had.
Choi hasn't had a victory since the 2012 US Women's Open but had no bad feelings at finishing runner-up to Ryu.
"Sometimes I finish runner-up and sometimes I have a lot of regrets, but this week not really," Choi said. "She's playing well."
World number two Park Inbee, the LPGA Championship winner, finished in third meaning the top three players were South Korean with Azahara Munoz a stroke adrift in fourth.